Patent Description:
The present invention relates to the field of brake by wire braking systems for vehicles.

In known brake by wire systems, the actuation of the braking devices does not take place by direct action of the driver, but the user's request for braking action, typically acting on a lever or pedal, is converted into drive by electromechanical means which act on the braking devices, such as for example disc brake calipers.

Autonomous braking systems are also known in which the steering system of the vehicle decides the timing and the amount of braking and consequently actuates said electromechanical means connected to the braking devices.

For obvious safety reasons, braking systems must provide a back-up strategy to be implemented in the event of an electrical fault of at least one braking device and/or the relative actuators.

In this regard, brake-by-wire braking systems are known, for example, in which, in the event of an electrical fault, the braking action is exerted mechanically, conventionally, i.e. by fluidically connecting the lever or pedal operated by the user to request the braking action, directly with said braking devices.

However, these systems have the drawback of requiring both the electrical system to be always operated under standard operating conditions, and the hydraulic system to be operated in the event of an electrical fault. The presence of the hydraulic system involves an increase in costs, masses, the management of highly hygroscopic hydraulic fluid, the management and maintenance of hydraulic fluid seals and so on.

In addition, hydraulic back-up solutions are not applicable to self-driving vehicles and do not always guarantee maximum braking efficiency in the event of hydraulic back-up.

There are also full-electric solutions that do without the hydraulic part of the braking system and that, in the event of an electrical fault, put in place back-up strategies to ensure a partial restoration of the braking capacity of the system and therefore the performance of the braking itself, although non-optimal. However, these solutions are not optimal and, in the event of a fault, do not always guarantee optimal braking. Solutions according to prior art are disclosed, for example, by <CIT>.

The need to solve the drawbacks and limitations mentioned with reference to the prior art is therefore increasingly felt.

This requirement is met by a braking system for vehicles according to claim <NUM>.

In particular, this need is met by a braking system for vehicles comprising.

According to an embodiment, the first control unit is operatively connected also to the third brake group by means of a piloting device for the electromechanical or electro-hydraulic actuator of the third brake group.

According to an embodiment, the electromechanical actuator comprises a <NUM>-phase electric motor which pilots said third brake group, wherein the first and second control units comprise a piloting device operatively connected to said <NUM>-phase electric motor and capable of actuating it.

According to the invention the first control unit is operatively connected to the first brake group, to the second brake group and to the third brake group by means of three relative piloting devices, wherein the second control unit is operatively connected to the first brake group, to the second brake group and to the third brake group by means of a three relative piloting devices, said piloting devices being independent of each other.

According to an embodiment, each brake group is piloted by a <NUM>-phase electric motor connected to pairs of piloting devices, each piloting device of said pair being controlled by a relative control unit.

According to an embodiment, the system comprises a first and a second manual actuation device for a request for a braking action by a user, wherein both the manual actuation devices are provided with two actuation sensors, a first actuation sensor being connected to the first control unit and a second actuation sensor being connected to the second control unit.

According to an embodiment, each control unit is connected to said first and second power sources so that it can be alternately powered by each of said power sources in the event of a fault of one of them.

According to an embodiment, an additional control unit programmed to manage the power supply of each control unit is provided.

According to an embodiment, each piloting device is programmed to switch from a first switch position, corresponding to the standard braking strategy, to a second switch position corresponding to the fault-braking strategy.

According to an embodiment, the first and the second control units are operatively connected to each other so that each knows the type of operation, standard or fault, implemented by the other control unit.

According to an embodiment each electromechanical actuator is equipped with an operating sensor suitable to monitor the operating condition of the relative electromechanical or electro-hydraulic actuator and/or of the relative braking device and to send the corresponding control unit an indication of standard or fault operation.

According to an embodiment the control units are programmed so that in case of fault of a brake group, the actuation of the remaining brake groups is ensured and coordinated.

According to an embodiment, the control units are programmed so that in the event of a fault of one brake group the actuation of the remaining brake units is guaranteed, and wherein the braking system is operatively connected to a piloting device of the vehicle, so as to coordinate the actuation of the piloting device with the actuation of the operating brake units.

According to an embodiment, the control units are programmed so that in the event of a fault in a brake group, the operation of the remaining brake groups is guaranteed and coordinated, wherein the braking system is operatively connected to electrical power generation means operatively connected to the brake groups so as to obtain an additional braking action of the vehicle.

According to an embodiment each electromechanical or electro-hydraulic actuator is equipped with two operating sensors, each suitable to monitor the operating condition of the relative electromechanical actuator and/or of the relative braking device and to send an indication of standard or fault operation to both the control units.

According to an example the system is managed by a control unit of the vehicle which manages vehicle dynamics and is able to perform guidance and an independent braking action of the same.

Further features and advantages of the present invention will appear more clearly from the following description of preferred non-limiting embodiments thereof, in which:
<FIG> represent schematic views of possible embodiments of a braking system according to the present invention.

Elements or parts of elements in common to the embodiments described below are referred to with the same reference numerals.

With reference to the above figures, reference numeral <NUM> globally denotes a braking system for vehicles.

For the purposes of the present invention, vehicles means motor vehicles equipped with at least two wheels.

In particular, the vehicle braking system <NUM> comprises at least a first brake group <NUM>, a second brake group <NUM> and a third brake group <NUM>.

Said first, second and third brake groups <NUM>, <NUM>, <NUM> can each be associated with a distinct wheel (not shown), in the case of three-wheeled vehicles, for the relative braking thereof.

In the case of a two-wheeled vehicle, it is possible to associate two brake groups to the same wheel (for example the front wheel of a motorcycle) and a brake group to the other wheel (for example the rear wheel).

According to the present invention, said brake groups are associated with wheels arranged on different axles of the vehicle, such as for example a front axle and a rear axle of the vehicle itself. In the case of a two-wheeled vehicle, two brake groups must be mounted on the same axle.

Each brake group <NUM>, <NUM>, <NUM> comprises a rotor <NUM> which rotates integrally with the wheel to be braked and a braking device <NUM> configured for braking said rotor <NUM> and the corresponding wheel.

The type of rotor depends on the type of braking device used.

For example, in the case of a braking device of the drum brake type, the rotor will comprise a bell, in the case of a braking device <NUM> with disc brake, the rotor <NUM> will comprise a brake disc, in a known manner.

Each brake group <NUM>, <NUM>, <NUM> further comprises electromechanical or electro-hydraulic actuators <NUM> of each braking device <NUM>.

The electromechanical or electro-hydraulic actuators <NUM> may comprise electric motors configured in such a way as to enable and disable the braking devices <NUM>. For example, said electromechanical actuator means <NUM> may comprise an electric motor connected, by means of a worm screw mechanism, to a pusher for at least one piston acting on a pad of a disk brake caliper.

In the case of electro-hydraulic actuators, it is possible to provide for the use of mechanical means which pressurize a fluid which in turn actuates, remotely, said braking devices <NUM>.

Advantageously, the braking system <NUM> comprises a first and a second control unit <NUM>,<NUM> for said brake groups <NUM>,<NUM>,<NUM>.

According to an embodiment (<FIG>), the first control unit <NUM> is operatively connected to the first brake group <NUM> by means of a piloting device <NUM> for said electromechanical or electro-hydraulic actuator <NUM> of the first brake group <NUM>.

Moreover, the second control unit <NUM> is operatively connected to the second brake group <NUM> by means of a piloting device <NUM> for said electromechanical or electro-hydraulic actuator <NUM> of the second brake group <NUM>, and is connected to the third brake group <NUM> by means of a piloting device <NUM> for electromechanical or electro-hydraulic actuator <NUM> of the third brake group <NUM>.

In this way, a control unit controls only one brake group (for example the first one) and the other control unit controls two brake groups, for example the second and the third.

Preferably, the piloting devices <NUM> of the various brake groups <NUM>, <NUM>, <NUM> are electrically and mechanically independent and separate from each other.

The first control unit <NUM> is connected to and powered by a first power source <NUM>, and the second control unit <NUM> is connected to and powered by a second power source <NUM>.

Advantageously, said first and second power sources <NUM>,<NUM> are independent and galvanically isolated from each other.

The power source is typically a lead battery, a lithium ion battery and the like.

The separate power supply of said power sources <NUM>, <NUM> guarantees the correct operation of at least one brake group <NUM>, <NUM>, <NUM> in the event of an electrical fault of one of said power sources <NUM>, <NUM>.

Preferably, each control unit <NUM>,<NUM> is connected to said first and second power sources <NUM>,<NUM> so that it can be alternately powered by each of said power sources <NUM>,<NUM> in the event of a fault of one of them. In this way, the fault of a power source does not affect the operation of any control unit <NUM>, <NUM>, of the respective piloting devices <NUM> and electromechanical and/or electro-hydraulic actuators <NUM>.

For example, an additional control unit <NUM> or a dedicated electronic circuit programmed to manage the power supply of each control unit <NUM>,<NUM> is provided.

In particular, each control unit <NUM>,<NUM> is programmed to implement, via the corresponding piloting system <NUM>, a standard braking strategy in case of malfunctions for each brake group <NUM>, <NUM>, <NUM> and a fault braking strategy, if it detects an electrical fault of one or more of the brake groups <NUM>, <NUM>, <NUM>.

standard operation means a normal operating condition in which there are no anomalies in the braking system that is able to exert the braking action requested by the user or by the autonomous driving system of the vehicle (if provided).

Electric fault condition means a malfunction of a brake group <NUM>,<NUM>,<NUM>, for example of the power sources <NUM>,<NUM>, of the piloting devices <NUM>, of the electromechanical or electro-hydraulic actuators <NUM> that partially or totally prevents the operation thereof.

Moreover, "fault" means a generic condition of malfunction which may include a problem both to the mechanical components (braking devices <NUM> and/or electromechanical or electro-hydraulic actuators <NUM>) and to the electrical/electronic components, but may also comprise a software problem of management of the control unit <NUM>,<NUM>, reading of the data concerning the operation of the braking system <NUM> and the like.

Each piloting device <NUM> is programmed to switch from a first switch position, corresponding to the standard braking strategy, to a second switch position corresponding to the fault-braking strategy.

Preferably, the first and the second control units <NUM>,<NUM> are operatively connected to each other so that each knows the type of operation, standard or fault, implemented by the other control unit <NUM>,<NUM>.

In this way, each control unit allows the operation of the other unit and of the respective devices connected to it, so as to have information on the operation of the entire braking system <NUM>.

Preferably, the control units <NUM>,<NUM> are programmed so that in case of fault of a brake group, the actuation of the remaining brake groups is ensured and coordinated.

According to an embodiment, the control units <NUM>,<NUM> are programmed so that in the event of a fault of one brake group the actuation of the remaining brake units is guaranteed, and the braking system <NUM> is operatively connected to a piloting device of the vehicle (not shown), so as to coordinate the actuation of the piloting device with the actuation of the operating brake units. In this way, it is possible to obtain a complete management of the vehicle stability control.

According to a further possible embodiment, the control units <NUM>,<NUM> are programmed so that in the event of a fault in a brake group, the operation of the remaining brake groups is guaranteed and coordinated, and the braking system is operatively connected to electrical power generation means operatively connected to the brake groups so as to obtain an additional braking action of the vehicle.

In other words, due to regenerative braking, it is possible to obtain a further braking effect which can compensate for malfunctions of the brake groups applied to each wheel.

The braking system <NUM> may also be managed by a control unit of the vehicle which manages vehicle dynamics and is able to perform guidance and an independent braking action of the same.

In the embodiments of <FIG>, the braking system always guarantees the operation of a brake group <NUM>, <NUM>, <NUM> in the event of an electrical fault.

According to a possible embodiment (<FIG>), the first control unit <NUM> is operatively connected not only to the first brake group <NUM> but also to the third brake group <NUM> by means of a piloting device <NUM> for the electromechanical or electro-hydraulic actuator <NUM> of the third brake group <NUM>.

For example, in this embodiment (<FIG>), the electromechanical or electro-hydraulic actuators <NUM> comprise a <NUM>-phase electric motor <NUM> which pilots said third brake group <NUM>, wherein the first and second control units <NUM>,<NUM> are connected to a piloting device <NUM> operatively connected to said <NUM>-phase electric motor <NUM>.

The braking system of <FIG>, in the event of an electrical fault, guarantees the operation of two brake groups <NUM>,<NUM>,<NUM>.

According to a further embodiment (<FIG>), the first control unit <NUM> is operatively connected to the first brake group <NUM>, the second brake group <NUM> and the third brake group <NUM> by means of three relative piloting devices <NUM>. Moreover, the second control unit <NUM> is operatively connected to the first brake group <NUM>, the second brake group <NUM> and the third brake group <NUM> by means of three relative piloting devices <NUM>, said piloting devices <NUM> being independent of each other.

In this embodiment, each brake group <NUM>,<NUM>,<NUM> is piloted by a <NUM>-phase electric motor <NUM> connected to pairs of piloting devices <NUM>, each piloting device <NUM> of said pair being controlled by a relative control unit <NUM>,<NUM>.

The braking system of <FIG>, in the event of an electrical fault, guarantees the operation of all the three brake groups <NUM>,<NUM>,<NUM>.

The braking system <NUM> according to the present invention usually comprises a first and a second manual actuation device <NUM>,<NUM> for the request of braking action by a user.

Preferably, both manual actuation devices <NUM>,<NUM> are equipped with two actuation sensors <NUM>,<NUM>, a first actuation sensor <NUM> being connected to the first control unit <NUM> and a second actuation sensor <NUM> being connected to the second control unit <NUM>. Thus, in a vehicle in which there are two independent brake controls (for example a motorcycle) in the event of a failure of a control unit, the other can continue to brake according to both requests received through both controls.

According to an embodiment, each electromechanical or electro-hydraulic actuator <NUM> is equipped with an operating sensor <NUM> suitable to monitor the operating condition of the relative electromechanical or electro-hydraulic actuator <NUM> and/or of the relative braking device <NUM> and to send the corresponding control unit <NUM>,<NUM> an indication of standard or fault operation.

According to a further embodiment each electromechanical or electro-hydraulic actuator <NUM> is equipped with two operating sensors <NUM>, each suitable to monitor the operating condition of the relative electromechanical or electro-hydraulic actuator <NUM> and/or of the relative braking device <NUM> and to send an indication of standard or fault operation to both the control units <NUM>,<NUM>.

It should be noted that the operational connections between the various electrical, electromechanical components of the devices of the braking system <NUM> according to the invention may take place by means of an electric line and/or a data transmission line <NUM>, for example of the CAN type. In this way, the control units, having detected a fault condition, can manage the vehicle braking by implementing the fault strategy.

As can be appreciated from the foregoing, the braking system for vehicles according to the invention overcomes the drawbacks of the prior art.

In fact, the braking system allows completely eliminating the part of hydraulic backup and in general of backup that requires the manual intervention of the operator typical of traditional braking systems without losing in reliability or safety, even in case of fault.

The elimination of the backup part of the system allows reducing overall the system masses, the hydraulic lines and all the sealing problems connected to them. Furthermore, it is not necessary to periodically replace the braking fluid, due to its strong hygroscopicity.

Furthermore, the system of the present invention lends itself well to being integrated into a self-driving or in any case assisted-drive full-electric vehicle, in which the braking action can be controlled autonomously by a control unit which is responsible for driving and controlling the vehicle.

Furthermore, the system of the present invention also lends itself well to non-autonomous driving solutions in which the user manually requests the braking action.

Furthermore, the braking system guarantees the safety of the braking even in the event of an electrical fault.

With regard to the operation of the brake groups in the event of an electrical fault, the present invention provides three embodiments with different operating safety devices, in particular:.

Moreover, as seen, it is possible to compensate for malfunctions of a wheel group either by acting on vehicle steering control systems or by acting on regenerative braking devices.

In the first case, a vehicle check is carried out, for example to correct yawing phenomena, in the second case an additional braking action is obtained to reduce the speed thereof. Obviously, the two actions may be combined with each other.

Therefore, the system of the present invention has the same level of reliability and safety of a traditional hydraulic braking system, without the drawbacks of hydraulic backups and without the need for manual backup by an operator, with the advantage that it can also be used on a self-driving vehicle.

Claim 1:
Braking system for vehicles (<NUM>) comprising
- a first brake group (<NUM>), a second brake group (<NUM>) and a third brake group (<NUM>),
- each brake group (<NUM>, <NUM>, <NUM>) comprising a rotor (<NUM>), a braking device (<NUM>) associated with said rotor (<NUM>), and an electro-hydraulic or electromechanical actuator (<NUM>) of each braking device (<NUM>),
- a first and a second control unit (<NUM>,<NUM>) for said brake groups (<NUM>,<NUM>,<NUM>),
- wherein the first control unit (<NUM>) is operatively connected to the first brake group (<NUM>) by means of a piloting device (<NUM>) for said electromechanical or electro-hydraulic actuator (<NUM>) of the first brake group (<NUM>),
- wherein the second control unit (<NUM>) is operatively connected to the second brake group (<NUM>) by means of a piloting device (<NUM>) for said electromechanical or electro-hydraulic actuator (<NUM>) of the second brake group (<NUM>), and is connected to the third brake group (<NUM>) by means of a piloting device (<NUM>) for the electromechanical or electro-hydraulic actuator (<NUM>) of the third brake group (<NUM>),
- wherein the first control unit (<NUM>) is connected to and powered by a first power source (<NUM>), and wherein the second control unit (<NUM>) is connected to and powered by a second power source (<NUM>), said first and second power sources (<NUM>,<NUM>) being independent and galvanically isolated from each other,
- each control unit (<NUM>,<NUM>) being programmed to implement, via the corresponding piloting system (<NUM>), a standard braking strategy in case of absence of malfunctions for each brake group (<NUM>, <NUM>, <NUM>) and a fault braking strategy, if it detects an electrical fault of one or more of the brake groups (<NUM>, <NUM>, <NUM>),
wherein the first control unit (<NUM>) is operatively connected to the first brake group (<NUM>), the second brake group (<NUM>) and the third brake group (<NUM>) by means of three relative piloting devices (<NUM>),
wherein the second control unit (<NUM>) is operatively connected to the first brake group (<NUM>), the second brake group (<NUM>) and the third brake group (<NUM>) by means of three relative piloting devices (<NUM>), said piloting devices (<NUM>) being independent of each other,
wherein said first brake group (<NUM>), second brake group (<NUM>) and third brake group (<NUM>) are associated with wheels arranged on different axles of the vehicle.