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TEXT OF THE DESCRIPTION

Field of the invention

The present invention generally relates to the field of motor-vehicle braking systems. In particular, the invention has been developed with reference to systems for generating the hydraulic pressure for actuating brake devices of the wheels of a motor-vehicle.

Prior art

In the field of braking systems for vehicles, it is known to provide systems for actuating and modulating the hydraulic pressure, based on the pressure increase in the hydraulic circuit due to actuation of the brake pedal. The pressure is then transferred to the brake devices (brake calipers or drum) by the hydraulic circuit itself.

A conventional solution, for example, described in the document CN103318162A, envisages the use of a vacuum brake booster which acts on a brake system pump, amplifying the force exerted on the brake pedal by the driver.

An additional known solution is illustrated in Figures 1 , 2. These figures illustrate a hydraulic pressure actuation and modulation system integrated in a single unit, according to an architecture called “One Box”, which is currently particularly widespread for electric propulsion vehicles.

The expression “One Box” derives from the fact that the functions typically performed by the vacuum brake booster and the ESC control unit of the conventional solutions described above are incorporated in a single unit. The “One Box” solution, in addition to generating the braking pressure, is able to modulate the above for each wheel in poor grip conditions.

Figure 1 is a perspective view illustrating an embodiment example of a known solution according to the “One Box” architecture. Reference 1 indicates a single hydraulic and electromechanical unit for generating and modulating the hydraulic braking pressure for actuating the brakes of a motor-vehicle. Figure 2 is a diagram illustrating the components and operation of the unit 1 .

The hydraulic and electromechanical unit 1 comprises a fluid reservoir 3, a hydraulic unit 2 operatively in communication with the fluid reservoir 3 according to the following description, an electronic control unit E, a connecting rod 5 with a pedal brake P, and an electric motor 4 operatively connected to an electromechanical actuator 6.

Figure 2 illustrates an operating diagram of the system with the known type “One Box” architecture. The motor-vehicle on which the system is installed comprises at least one manually actuation element, such as a brake pedal P, operatively connected to an electronic control unit E, to transmit a braking action request to said electronic control unit E by means of the actuation of the pedal element P.

The system further comprises an actuator assembly 7 hydraulically connected by means of a hydraulic circuit H to the fluid reservoir 3 and to the brake devices B of the vehicle, such as a disc brake caliper or a drum. The actuator assembly 7 comprises an electromechanical actuator 6 which can be operated by the electric motor 4, in order to direct the pressurized fluid towards the brake devices B of the wheels of the motor-vehicle. The electronic control unit E is operatively connected to the actuator assembly 7 and is programmed so as to be able to selectively actuate the brake devices B by means of the actuation of the actuator assembly 7.

The reference 8 indicates a valve operatively connected and interposed between the fluid reservoir 3 and the actuator assembly 7. This valve 8 is in the normally open position to allow the passage of fluid towards the actuator assembly 7 and thus keep the hydraulic circuit H under pressure. The system also comprises a control valve 9 operatively interposed between the actuator assembly 7 and the brake devices B of the wheels of the motor-vehicle. In one or more embodiments, a sensor 10 is arranged upstream of the control valve 9, which detects the passage of fluid under pressure from the actuator assembly 7 towards the valve 9, and allows the valve 9 to open to let the fluid flow under pressure towards the brake devices B of the wheels of the motor-vehicle.

In one or more embodiments, the system comprises a further hydraulic circuit 11 interposed between the control valve 9 and the brake devices B, configured to modulate the fluid pressure generated upstream towards the respective wheels, according to the actual grip of the motorvehicle on the ground. The details relating to said further hydraulic circuit 11 are not illustrated as they can be made according to techniques widely known to the expert in the sector.

The known type of “One Box” architecture also envisages an auxiliary safety system for generating hydraulic braking pressure in the case of failure/malfunctioning of the electric motor 4 and/or of the electromechanical actuator 6. This auxiliary safety system takes the form of a connecting rod 5 with the brake pedal B, in order to comply with the legislative/approval requirements envisaged in the event of the aforesaid failure. The system therefore comprises a further actuator 12 directly connected to the brake pedal B by means of said connecting rod 5. The system also comprises a further valve 13 interposed between the fluid reservoir 3 and the further actuator 12, wherein the valve 13 is configured in the normally open position to allow the outflow of the fluid in the part of the circuit H relating to the auxiliary safety system. The system also comprises an additional valve 14 arranged downstream of the further actuator 12 and interposed between said further actuator 12 and the further circuit 11 for distributing the operating pressure to the respective brake devices B of the wheels of the motor-vehicle. The valve 14 can also be associated with a sensor 15 that detects the passage of fluid from the actuator 12, allowing the opening of the additional valve 14 to direct the pressurized fluid towards the further hydraulic circuit 11 and, therefore, towards the brake devices B of the motorvehicle wheels. The system also comprises a brake pedal simulator device 19 operatively in communication with the further actuator 12, arranged to simulate the force/stroke of the brake pedal P. A normally open valve 20 is interposed between the simulator device 19 and the further actuator 12, which can be switched to the closed position to isolate the simulator device 19 in the event of the aforesaid failure.

In the light of the above, during operation, in the case of failure of the electric motor 4 and/or of the electromechanical actuator 6, the hydraulic actuation pressure of the brakes is directed by means of the auxiliary safety system defined by the direct mechanical connection between the brake pedal P and the further actuator 12, created by means of the connecting rod 5. The hydraulic pressure generated corresponds to the stroke of the brake pedal P detected by a special sensor 18.

However, the use of such “One Box” architectures is not without its own drawbacks.

In the first place, the solution described above comprises a rod for mechanical connection to the brake pedal, as it is necessary to comply with the legislative/approval requirements which are envisaged in the case of failure of the electro-hydraulic part described above. This solution, due to the constraint of the direct mechanical connection with the brake pedal, obliges the installation of the single electromechanical hydraulic unit in the motor compartment downstream of the pedal unit, thus making the mounting specific for left-hand drive or right-hand drive vehicles. All this translates into a disadvantage in terms of cost and complexity, as the production of vehicles will have to be differentiated according to the type of drive. Therefore, these solutions have the limitation of having to respond to legislative/approval requirements, to the detriment of the simplicity of implementation and cost reduction.

An alternative solution, in this sense, would be useful for seeking the best compromise between maximum fulfillment of the legislative/approval requirements and reducing costs, without compromising operational reliability.

Object of the invention

The object of the invention is to solve the previously mentioned technical problems. In particular, the object of the invention is to provide a solution for generating the hydraulic pressure for actuating the brakes of a motor-vehicle braking system, complying with the legislative/approval requirements, together with the simplicity of construction and the relative cost reduction.

Summary of the invention

The object of the present invention is achieved by a system having the characteristics forming the subject of the claims that follow, which form an integral part of the technical disclosure given here in relation to the invention. Brief description of the figures

The invention will now be described with reference to the attached figures, provided purely by way of non-limiting example, wherein:

- Figure 1 illustrates a known solution of systems for generating the hydraulic pressure for actuating the brakes of a motor-vehicle, according to the “One Box” architecture,

- Figure 2 is an operating diagram of the solution illustrated in Figure 1 , and

- Figure 3 illustrates an operating diagram of a system for generating the hydraulic pressure for actuating the brakes, according to the present invention.

Detailed description of more embodiments

In the following description various specific details are illustrated aimed at a thorough understanding of examples of one or more embodiments. The embodiments can be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. The reference to “an embodiment” in the context of this description indicates that a particular configuration, structure or characteristic described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as “in an embodiment”, possibly present in different places of this description do not necessarily refer to the same embodiment. Moreover, particular conformations, structures or characteristics can be combined in a suitable manner in one or more embodiments and/or associated with the embodiments in a different way from that illustrated here, for example, a characteristic here exemplified in relation to a figure may be applied to one or more embodiments exemplified in a different figure.

The references illustrated here are only for convenience and do not, therefore, delimit the field of protection or the scope of the embodiments.

Figures 1 , 2 have already been described with reference to the conventional technique according to the “One Box” architecture. Figure 3 illustrates an operating diagram of a system for generating the hydraulic pressure for actuating the brakes of a motor-vehicle braking system, according to the present invention. In Figure 3, the components in common with the conventional technique are indicated with the same references.

Based on the invention, an alternative solution of an auxiliary safety system is proposed for generating the hydraulic braking pressure in the case of failure of the electric motor 4 and/or of the actuator 6.

In this regard, the system with “One Box” architecture according to the invention comprises an auxiliary electric motor 16 operatively connected to an auxiliary actuator 12, wherein the auxiliary electric motor 16 and the auxiliary actuator 12 are integrated within the casing defining the single electromechanical hydraulic unit 1 .

Compared to known solutions, there is, therefore, no direct mechanical connection between the brake pedal P and the auxiliary actuator 12.

According to the present invention, the electronic control unit E is configured and programmed to send an activation signal to the auxiliary electric motor 16, in the case of failure of the actuator assembly 7, to generate the hydraulic pressure and direct the pressurized fluid towards the brake devices B of the wheels of the motor-vehicle, without the provision of a direct mechanical connection between the brake pedal P and the auxiliary actuator 12. The reference 17 indicates a position sensor for detecting the position of the brake pedal P and communicating this position to the electronic control unit E. The position sensor 17 is operatively connected to a brake pedal feel simulator 21 .

During operation, following the movement of the pedal P, with a given pedal stroke detected by the position sensor 17, the electronic control unit E determines - in a predetermined way - the corresponding hydraulic pressure corresponding to the detected pedal stroke. The electronic control unit E therefore receives a position signal of the pedal P and controls the actuation of the electric motor M which develops the aforesaid corresponding hydraulic actuation pressure through the actuator 6. The hydraulic circuit H, already described in Figure 2, allows the outflow of hydraulic fluid towards the brake devices B of the wheels of the motorvehicle.

In the case of failure of the actuator assembly 7 detected by the electronic control unit E, the electronic control unit, having received the position signal of the brake pedal P, sends a command signal to operate the auxiliary electric motor 16, so as to operate the auxiliary actuator 12. Consequently, the operating pressure generated flows towards the brake devices B of the wheels of the motor-vehicle by means of the valve 14, which is opened to allow the passage of hydraulic fluid under pressure.

Of course, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the present invention as defined by the claims that are attached.