Braking system for a brake-by-wire braking set for vehicles, braking set and control method

Abstract

A braking system for a brake-by-wire braking set for vehicles comprises an absorber body (10) with an absorber chamber (14) containing hydraulic fluid, a first fluid connection (4) for the exchange of fluid between the absorber chamber (14) and a fluid tank (1), a plunger (5) urged by a manual drive device (2), a movable component (8) connected to the plunger (5) by means of a first elastic member (6), and a second elastic member (7) counteracting the movement of the movable component (8). A blocking mechanism (80) limits the sliding of the movable component (8) in one direction, bypassing the action of the second elastic member (7). The system includes an actuator group (30) for pressurising the hydraulic fluid, a tank valve (20) for controlling the fluid flow, and a displacement sensor (12) or a pressure sensor (11) for detecting the movement of the plunger (5).

Description

"BRAKING SYSTEM FOR A BRAKE— BY— WIRE BRAKING SET FORVEHICLES, BRAKING SET AND CONTROL METHOD" DESCRIPTIONFIELD OF APPLICATION

[0001] The present invention relates to a braking system for a brake-by-wire braking set for vehicles , a brake-by- wire braking set and a method for controlling the braking system .STATE OF THE ART

[0002] Brake-by-wire braking systems currently available for vehicles , and in particular for motorcycles , are composed of three main subassemblies : the driver control, a feedback system and an actuation system . The driver control, consisting of a lever or a pedal, is connected to a component that acts on the hydraulic fluid . The feedback system receives the hydraulic fluid and provides resistance feedback to the driver through a spring system . The actuation system, connected to the mechanical components that perform the braking action, moves the hydraulic fluid, for example by transforming the rotary movement of an electric motor into linear movement to displace the hydraulic fluid .

[0003] In brake-by-wire braking systems , the actuation system is generally electrically connected to the rest of the braking system, but not hydraulically . This meansthat the force exerted by the driver on the lever or pedal is converted into an electric signal via pressure, force or displacement transducers . This signal is then processed by a control unit that controls the actuators of the braking system . Since the two systems are separate, the brake master cylinder is replaced by a master cylinder simulator, also referred to as absorber, i . e . , a device that simulates the feel and stiffnes s that a driver perceives when pressing the brake control in a conventional hydraulic braking system .

[0004] These systems present several drawbacks . One of the main drawbacks is the large number of components distributed among three distinct subassemblies , resulting in significant bulk and added weight . This is particularly problematic for motorcycles , where available space is limited and low weight is a fundamental requirement . Furthermore, placing the centre of gravity as close to the ground as possible is desirable for the manoeuvrability of the motorcycle, but the space in the lower part of the motorcycle is occupied by components related to the engine, forcing the additional weight to be placed higher up .

[0005] A general reduction in volume and mass is therefore desirable .

[0006] Therefore, there is a strong need in the field for abrake-by-wire braking system that reduces the overall number of components , bulk and weight , while ensuring appropriate braking feel for the driver .

[0007] Furthermore, a further object of the present invention is to ensure that the driver is able to manually pressurise the braking system using the driver control ( lever or pedal ) even in the event of a fault or anomaly, i . e . , to ensure the presence of a backup braking system even in the event of a failure or absence of electric power .SUMMARY OF THE INVENTION

[0008] The need for a braking system for a brake-by-wire braking set for a vehicle is met by a braking system, a braking set and a control method according to the attached independent claims .

[0009] According to one embodiment , the braking system for a brake-by-wire braking set for a vehicle comprises an absorber body comprising an absorber chamber containing a hydraulic fluid; a first fluid connection configured to permit exchange of hydraulic fluid between the absorber chamber and a fluid tank; a plunger contained in the absorber chamber suitable for being urged by a manual drive device ; a movable member, sliding in the absorber chamber along a main direction and connected to the plunger by means of a first elastic member; a secondelastic member secured on one side to the absorber body and on the other side to the movable member, said second elastic member being positioned to at least partially counteract the movement of the movable member in a first sliding orientation of the two sliding orientations along the main direction; a blocking mechanism configured to restrict or prevent sliding of the movable member in the first sliding orientation along the main direction upon reaching a predetermined position of the movable member, so as to bypass the counteracting action of the second elastic member .

[0010] According to one embodiment , the blocking mechanism comprises a sealing interface between the movable member and the absorber body, configured to divide the absorber chamber into a first sub-chamber and a second sub-chamber which define two separate volumes ; a second fluid connection, configured to permit exchange of hydraulic fluid between the first sub-chamber and a fluid tank when the movable member is in a resting position, said second fluid connection being configured to be closed by effect of displacement of the movable member so as to determine fluid isolation of the second sub-chamber from the fluid tank .

[0011] According to one embodiment , the first fluid connection is configured to permit exchange of hydraulicfluid between the first absorber sub-chamber and the fluid tank .

[0012] According to one embodiment , the braking system comprises an actuator group hydraulically connected to the absorber body and configured to pressurise the hydraulic fluid in the actuator chamber via an actuator piston, said actuator piston being suitable for being actuated by an actuator, for example an electric actuator such as a rotary electric motor .

[0013] According to one embodiment , the braking system comprises a tank valve configured to control fluid flow between the absorber body and the fluid tank, said tank valve being kept open during normal operation of the braking system; a displacement sensor or a pressure sensor configured to detect movement of the plunger .

[0014] According to one embodiment , the fluid tank is built into the absorber body .

[0015] According to one embodiment , the fluid tank is removable to facilitate maintenance .

[0016] According to one embodiment , the tank valve is normally closed in case of absence of electric power .

[0017] According to one embodiment , the braking system comprises an electronic control unit configured to receive a signal detecting a movement of the plunger from the displacement sensor or from the pressure sensor andsend an electric actuator trigger signal that moves the actuator piston; moreover, the electronic control unit is configured to, upon detection of the movement of the plunger, send a signal interrupting the fluid connection between the actuator chamber and the absorber body, before fluid isolation of the second sub-chamber from the fluid tank takes place .

[0018] According to one embodiment , the electronic control unit is configured to receive a signal indicating a fault or anomaly and, upon receipt of said signal indicating a fault or anomaly, said electronic control unit is configured to send an electrical power interruption signal or to directly interrupt the electrical power towards the tank valve so as to close the tank valve and prevent the flow of hydraulic fluid between the absorber body and the fluid tank .

[0019] According to the invention, a brake-by-wire braking set comprises a braking system according to any one of the embodiments described herein and a braking group hydraulically connected to the actuator group for performing the braking action on a vehicle wheel .

[0020] According to another aspect of the invention, a method for controlling a brake-by-wire braking system for vehicles comprises the following operating steps :- providing a braking system according to any one ofthe embodiments described in this document ;- detecting a movement of the plunger via the displacement sensor or the pressure sensor and activating the electric actuator moving the actuator piston;- upon detecting the movement of the plunger, immediately interrupting the fluid connection between the actuator chamber and the absorber body, before fluid isolation of the second sub-chamber from the fluid tank takes place .

[0021] According to one embodiment , the method comprises the step in which, in the event of a fault or anomaly, the electrical power to the tank valve is interrupted so as to close the tank valve and prevent the flow of hydraulic fluid between the absorber body and the fluid tank .

[0022] According to one embodiment , the method comprises , upon detecting the movement of the plunger, moving the actuator piston by a first distance lower than a second distance travelable by the movable member in order to close the second fluid connection between the second subchamber and the fluid tank .DESCRIPTION OF THE DRAWINGS

[0023] Further features and advantages of the present invention will become more apparent from the following description of preferred, non-limiting embodimentsthereof , in which :- Figure 1 shows a schematic view of a braking set including a braking system according to one embodiment of the present invention .DETAILED DESCRIPTION

[0024] With reference to the above-mentioned figures , the reference number 100 globally denotes a braking system for a brake-by-wire braking set 200 .

[0025] The braking system 100 comprises an absorber body 10 , for example a cylinder, comprising an absorber chamber 14 housing a hydraulic fluid .

[0026] According to a first embodiment , illustrated for example in Figure 1 , a fluid tank 1 is connected to the absorber body 10 via a first fluid connection 4 and a second fluid connection 3 , for example one or more openings formed in the absorber body 10 .

[0027] According to one embodiment , a sealing interface 9 between the movable member 8 and the absorber body 10 is configured to divide the absorber chamber 14 into a first sub-chamber 141 and a second sub-chamber 142 , defining two separate volumes . In other words , the first subchamber 141 is isolated from the second sub-chamber 142 and passage of hydraulic fluid between the first subchamber 141 and the second sub-chamber 142 is not permitted, except through the fluid tank 1 .

[0028] According to one embodiment , the sealing interface 9 comprises a gasket or an O-ring installed on the movable member 8 , slidable along an inner lateral surface defining the absorber chamber 14 of the absorber body 10 .

[0029] According to one embodiment , a first fluid connection 4 is configured to permit exchange of hydraulic fluid between the absorber chamber 14 and the fluid tank 1 . In particular, the first fluid connection 4 is configured to permit exchange of hydraulic fluid between the first absorber sub-chamber 141 and the fluid tank 1 . A second fluid connection 3 is configured to permit exchange of hydraulic fluid between the second sub-chamber 142 and the fluid tank 1 when the movable member 8 is in its resting position . The second fluid connection 3 is configured to be closed by effect of displacement of the movable member 8 so as to determine fluid isolation of the second sub-chamber 142 from the fluid tank 1 .

[0030] The braking system 100 also comprises a plunger 5 contained in the absorber chamber 14 of the absorber body 10 , to which a manual drive device 2 , i . e . , a lever or a pedal, is suitable to be connected or is connected . The movement of the plunger 5 inside the absorber chamber 14 is counteracted by a first elastic member 6, for example a first spring, connecting the plunger 5 to the movablemember 8 . The movable member 8 is slidable in the absorber chamber 14 along a main direction X and is connected to the plunger 5 via the first elastic member 6 . A second elastic member 7 , for example a second spring, is secured on one side to the absorber body 10 and on the other side to the movable member 8 . The second elastic member 7 is positioned to at least partially counteract the movement of the movable member 8 in a first sliding orientation XI of the two sliding orientations XI , X2 along the main direction X . In particular, the first sliding orientation XI is opposite to a second sliding orientation X2 , along the same main direction X .

[0031] The braking system 100 also comprises a blocking mechanism 80 , configured to restrict or prevent sliding of the movable member 8 in the first sliding orientation XI along the main direction X upon reaching a predetermined position of the movable member 8 , so as to bypass the counteracting action of the second elastic member 7 . This occurs in particular when the second fluid connection 3 is closed by effect of the displacement of the movable member 8 , caused by displacement of the plunger 5 , so as to determine fluid isolation of the second sub-chamber 142 from the fluid tank 1 .

[0032] According to one embodiment , the absorber body 10 isthus connected to a fluid tank 1 via two connections , a first fluid connection 4 ( for example an opening formed in the absorber body 10 , for example in the cylinder) positioned between the plunger 5 and the movable member 8 along the main direction X, and the second fluid connection 3 ( for example a second opening formed in the absorber body 10 , for example in the cylinder) positioned between the movable member 8 and a bottom wall 181 of the absorber body 10 along the main direction X .

[0033] For example, the bottom wall 181 is a wall perpendicular to the inner lateral surface defining the absorber chamber 14 of the absorber body 10 . For example, it is the base wall of the absorber body 10 when it is a cylinder .

[0034] Preferably, during the entire stroke of the plunger 5 , the first fluid connection 4 remains always open, so as to act as a calibrated orifice to dampen the system . The second fluid connection 3 instead, after a short stroke, is occluded by the sealing interface 9 by effect of the position change of the movable member 8 . During the very first part of the stroke, when both connections 3 , 4 with the fluid tank 1 are open, the reaction force, provided by the system to the force applied by the driver through the manual drive device 2 , is given by the series of the first elastic member 6 and the second elasticmember 7 . Almost immediately, after a short stroke, the second fluid connection 3 closes and the fluid volume of the second sub-chamber 142 , i . e . , for example between the movable member 8 and the bottom wall of the absorber body 10 , behaves like a rigid body . In this phase, therefore, the elastic behaviour of the system is guaranteed only, or almost exclusively, by the first elastic member 6 .

[0035] The braking system 100 comprises an actuator group 30 hydraulically connected to the absorber body 10 and configured to pressurise the hydraulic fluid in the actuator chamber 50 via an actuator piston 40 . The actuator piston 40 is suitable for being actuated by an electric actuator, for example a linear electric actuator or a rotary electric motor associated with a mechanism for converting rotary motion into linear motion .

[0036] The braking system 100 also comprises a tank valve 20 configured to control the fluid flow between the absorber body 10 and the fluid tank 1 . Said tank valve 20 is kept open during normal operation of the braking system .

[0037] The braking system 100 also comprises a displacement sensor 12 , or a pressure sensor 11 , configured to detect the movement of the plunger 5 . Preferably, the displacement sensor 12 , or the pressure sensor 11 , is configured to send a signal configured to activate theelectric actuator to move the actuator piston 40 .

[0038] According to one embodiment , the pressure sensor 11 is configured to measure the pressure of the fluid in the second sub-chamber 142 .

[0039] In Figure 1 both the displacement sensor 12 and the pressure sensor 11 are shown, but it is clear that it is provided that in one embodiment there may be only the displacement sensor 12 or only the pressure sensor 11 , or both .

[0040] According to one embodiment , the braking system 100 comprises an electronic control unit 70 , for example an electronic processing and control unit comprising an electronic processor, configured to receive an electric signal from the pressure sensor 11 or from the displacement sensor 12 and to calculate a signal indicating a braking action proportional to the electric signal from the pressure sensor 11 or from the displacement sensor 12 to be sent to an actuator group 30 of the braking set 200 .

[0041] Preferably, the electronic control unit 70 is configured to receive an electric signal from the pressure sensor 11 or from the displacement sensor 12 and to send a signal configured to activate the actuator, for example an electric actuator, to move the actuator piston 40 .

[0042] To understand the operation of the braking system reference may be made, for example, to Figure 1 . I f the system is operating correctly, the brake-by-wire mode is available . In this case, the tank valve 20 , normally closed, remains open, for example thanks to an electric power supply . When the driver acts on the manual drive device 2 (the brake lever or pedal ) , the plunger 5 moves . Therefore, the braking process can be divided into different phases . In the initial phase, both the volumes of the first sub-chamber 141 and of the second subchamber 142 inside the absorber body 10 are in communication with the fluid tank 1 and the actuator chamber 50 . The displacement sensor 12 or the pressure sensor 11 located in the absorber body 10 immediately detects the movement of the plunger 5 and activates the electric actuator that moves the actuator piston 40 .

[0043] The movement of the actuator piston 40 immediately interrupts the fluid connection between the actuator chamber 50 and the hydraulic fluid volumes in the absorber body 10 , travelling a first distance (a) before the movable body 8 in the absorber body 10 covers a second distance (b) . In fact , once the movable body 8 has travelled the second distance (b) , for example in the first sliding orientation XI , fluid isolation of the pressurised fluid volume in the second sub-chamber 142from the fluid tank 1 occurs .

[0044] While the movable component 8 travels the second distance (b) , both fluid volumes of the first sub-chamber 141 and the second sub-chamber 142 are at the same pressure, for example ambient pressure, since they are directly connected to the fluid tank 1 . During this phase, the resistance to the movement of the plunger 5 is provided by the combined action of the series of the first elastic member 6 and the second elastic member 7 .

[0045] Once the second distance (b) is completed, the movable component 8 interrupts the fluid connection between the second sub-chamber 142 and the tank 1 . In this phase, the resistance to the movement of the plunger 5 is provided only by the spring 6, since the pressurised fluid in the second sub-chamber 142 is incompressible and communicates only with an actuator sub-chamber 31 isolated within the actuator chamber 50 of the actuator group 30 , which is also under pressure .

[0046] It is important that the first distance (a) is smaller than the second distance (b) because, during the brake release phase, when the plunger 5 , the movable component 8 and the actuator piston 40 move backwards , if the first distance (a) were greater than the second distance (b) , there would be a moment in which the fluid connection between the second sub-chamber 142 and theactuator chamber 50 would remain open, while the fluid connection between the sub-chamber 142 and the fluid tank 1 would be closed . This would result in pressurised fluid returning from the sub-chamber 142 into the actuator chamber 50 , destabilising the release phase of the manual drive device 2 (the brake lever) .

[0047] I f correct operation of the system is not ensured due to a fault , the brake-by-wire mode is disabled . In this case, the tank valve 20 , normally closed, ceases to receive power and prevents the flow of fluid between the absorber body 10 and the fluid tank 1 . In this operating condition, the actuator piston 40 remains stationary and retracted, thereby allowing the movement of the plunger 5 to directly pressurise the hydraulic fluid in the actuator chamber 50 and to perform braking, since with this configuration there is a direct fluid connection between the absorber chamber 14 of the absorber body 10 and the braking group 60 which performs the actual braking action ( for example, the brake callipers ) .

[0048] According to one embodiment , the electronic control unit 70 is configured to :- receive a signal detecting a movement of the plunger 5 from the displacement sensor 12 or from the pressure sensor 11 and send a signal to activate the electric actuator that moves the actuator piston 40 ;- upon detection of the movement of the plunger 5 , send a signal to interrupt the fluid connection between the actuator chamber 50 and the absorber body 10 , before fluid isolation of the second sub-chamber 142 from the fluid tank 1 takes place .

[0049] According to one embodiment , the electronic control unit 70 is configured to receive a signal indicating a fault or anomaly and, upon receipt of said signal indicating a fault or anomaly, said electronic control unit 70 is configured to send an electrical power interruption signal or to directly interrupt the electrical power to the tank valve 20 so as to close the tank valve 20 and prevent the flow of hydraulic fluid between the absorber body 10 and the fluid tank 1 .

[0050] It is clear that the present invention is also directed to a brake-by-wire braking set 200 comprising a braking system according to any one of the embodiments described herein and a braking group 60 hydraulically connected to the actuator group 30 for performing the braking action on a vehicle wheel . For example, the braking group 60 may comprise brake callipers or brake shoes .

[0051] Furthermore, the present invention also relates to a method for controlling a brake-by-wire braking system for vehicles , comprising the following operating steps :- providing a braking system according to any one of the variants described in this document ;- detecting a movement of the plunger 5 via the displacement sensor 12 or the pressure sensor 11 and activating the electric actuator that moves the actuator piston 40 ;- upon detection of the movement of the plunger 5 , immediately interrupting the fluid connection between the actuator chamber 50 and the absorber body 10 , before fluid isolation of the second sub-chamber 142 from the fluid tank 1 takes place .

[0052] According to one embodiment , the method comprises the step in which, in the event of a fault or anomaly, the electrical power to the tank valve 20 is interrupted so as to close the tank valve 20 and prevent the flow of hydraulic fluid between the absorber body 10 and the fluid tank 1 .

[0053] According to one embodiment , upon detection of the movement of the plunger 5 , it is provided to move the actuator piston 40 by a first distance (a) smaller than a second distance (b) travelable by the movable component 8 in order to close the second fluid connection 3 between the second sub-chamber 142 and the fluid tank 1 .

[0054] As can be appreciated from the foregoing description, the braking system and method according tothe invention make it possible to overcome the drawbacks of the known art .

[0055] Upon detection of the movement of the plunger, the method provides for the immediate interruption of the fluid connection between the actuator chamber and the absorber body before fluid isolation of the second subchamber from the fluid tank takes place .

[0056] The configuration of the braking system reduces the number of components by integrating the absorber and the driver control into a single subassembly, simplifying the overall architecture of the system . This is particularly advantageous for motorcycles where space and weight are critical constraints . The blocking mechanism ensures that the counteracting action of the second elastic member is bypassed at a predetermined position, providing a constant and reliable braking feel similar to traditional hydraulic systems .This design also enables manual backup pressurisation of the system in the event of actuator failure, improving safety and reliability .The arrangement of the plunger, the movable component and the elastic members within the absorber body ensures controlled and responsive braking action, enhancing the overall efficiency and safety of the vehicle braking system .

[0057] A person skilled in the art , in order to meet contingent and specific requirements , may make numerous modifications and variations to the invention described above, all of which are nonetheless contained within the scope of the invention as defined .

Claims

CLAIMS1. A braking system (100) for a brake-by-wire braking set for vehicle, comprising:- an absorber body (10) comprising an absorber chamber (14) containing a hydraulic fluid;- a first fluid connection (4) configured to permit exchange of hydraulic fluid between the absorber chamber (14) and a fluid tank (1) ;- a plunger (5) contained in the absorber chamber (14) suitable for being urged by a manual drive device (2) ;- a movable member (8) , sliding in the absorber chamber (14) along a main direction (X) and connected to the plunger (5) by means of a first elastic member (6) ;- a second elastic member (7) secured on one side to the absorber body (10) and on the other side to the movable member (8) , said second elastic member (7) being positioned to at least partially counteract the movement of the movable member (8) in a first sliding orientation (XI) of the two sliding orientations (XI, X2) along the main direction (X) ;- a blocking mechanism (80) configured to restrict or prevent sliding of the movable member (8) in the first sliding orientation (XI) along the main direction (X) upon reaching a predetermined position of the movable member (8) , so as to bypass the counteractingaction of the second elastic member (7) ; wherein the blocking mechanism comprises: o a sealing interface (9) between the movable member (8) and the absorber body (10) , configured to divide the absorber chamber (14) into a first sub-chamber (141) and a second sub-chamber (142) which define two separate volumes ; o a second fluid connection (3) , configured to permit exchange of hydraulic fluid between the first sub-chamber (141) and a fluid tank (1) when the movable member (8) is in a resting position (R) , said second fluid connection (3) being configured to be closed by effect of displacement of the movable member (8) so as to determine fluid isolation of the second sub-chamber (142) from the fluid tank ( 1 ) ; wherein the first fluid connection (4) is configured to permit exchange of hydraulic fluid between the first subchamber (141) and the fluid tank (1) ;- an actuator group (30) hydraulically connected to the absorber body (10) and configured to pressurize hydraulic fluid in the actuator chamber (50) via an actuator piston (40) , said actuator piston (40) being suitable for being actuated by an actuator;- a tank valve (20) configured to control fluid flow between the absorber body (10) and the fluid tank (1) ,said tank valve (20) being kept open during normal operation of the braking system;- a displacement sensor (12) or a pressure sensor (11) configured to detect movement of the plunger (5) .

2. Braking system (100) according to claim 1, wherein the fluid tank (1) is built into the absorber body (10) .

3. Braking system (100) according to claim 1, wherein the fluid tank (1) is removable to facilitate servicing.

4. Braking system (100) according to any one of the preceding claims, wherein the tank valve (20) is normally closed in case of absence of electric power.

5. Braking system (100) according to any one of the preceding claims, comprising an electronic control unit (70) configured to:- receive a signal detecting a movement of the plunger (5) from the displacement sensor (12) or from the pressure sensor (11) and send an electric actuator trigger signal suitable for moving the actuator piston (40) ;- upon detection of the movement of the plunger (5) , send a signal interrupting the fluid connection between the actuator chamber (50) and the absorber body (10) , before fluid isolation of the second sub-chamber (142) from the fluid tank (1) takes place.

6. Braking system (100) according to any one of thepreceding claims, wherein the electronic control unit(70) is configured to receive a signal indicating a fault or anomaly and, upon receipt of said signal indicating a fault or anomaly, said electronic control unit (70) is configured to send an electrical power interruption signal or to directly interrupt the electrical power towards the tank valve (20) so as to close the tank valve (20) and prevent the flow of hydraulic fluid between the absorber body (10) and the fluid tank (1) .

7. A brake-by-wire braking set (200) comprising a braking system (100) according to any one of the preceding claims and a braking group (60) hydraulically connected to the actuator group (30) for performing the braking action on a vehicle wheel.

8. A method for controlling a brake-by-wire braking system (100) for vehicles, comprising the following operating steps:- providing a braking system (100) according to any one of claims 1 to 6;- detecting a movement of the plunger (5) via the displacement sensor (12) or the pressure sensor (11) and activating the electric actuator moving the actuator piston (40) ;- upon detecting the movement of the plunger (5) , immediately interrupting the fluid connection between theactuator chamber (50) and the absorber body (10) , before fluid isolation of the second sub-chamber (142) from the fluid tank (1) takes place.

9. Method according to claim 8, comprising the step in which, in the event of a fault or anomaly, the electrical power to the tank valve (20) is interrupted so as to close the tank valve (20) and prevent the flow of hydraulic fluid between the absorber body (10) and the fluid tank ( 1 ) .

10. Method according to any one of the preceding claims, wherein, upon detecting the movement of the plunger (5) , it is provided that the actuator piston (40) is moved by a first distance (a) lower than a second distance (b) travelable by the movable member (8) in order to close the second fluid connection (3) between the second subchamber (142) and the fluid tank (1) .

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