Electromechanical brake actuator for a vehicle, in particular for at least one railway vehicle, and a braking system

Abstract

An electromechanical brake actuator (400) for a vehicle, in particular for a railway vehicle, is described, which comprises a safety unit (401) configured to receive an electrical position signal (221), the value of which indicates the position of a braking force application means (217) along a translation axis (Xt), and to determine the instantaneous position of the braking force application means (217) based on the value of the electrical position signal (221), and to prevent, via a first disconnection means (403), a braking force control signal (204) issued by a service brake control unit (202), or a power signal (405), from reaching the electromechanical module (201) when: a) the safety unit (401) determines that the braking force application means (217) is in a position between a maintenance position and a rest position, or b) the safety unit determines that the braking force application means (217) is moving from the rest position to the maintenance position.

Description

Technical Field

[0001] The present invention generally relates to the field of braking systems, and in particular, the present invention relates to an electromechanical brake actuator for a vehicle, in particular for at least one railway vehicle, and a braking system.

Background Art

[0002] In the following description, the following European standards are referred to according to the latest version available as of April 1, 2020. - EN50126 ["Railway applications - Reliability, availability, maintainability and safety (RAMS) specifications and demonstration"] - EN50128 ["Railway applications - Communication, signalling and processing systems - Software for railway control and protection systems"] - EN50129 ["Railway applications - Communication, signalling and processing systems - Safety-related electronic systems for signalling"] - EN50159 ["Railway applications - Communication, signalling and processing systems - Safety-related communication in transmission systems"]

[0003] In particular, the standard EN50126 defines a methodology for assigning safety levels SIL0 / 1 / 2 / 3 / 4 (where safety level SIL4 indicates the highest safety level) to the subsystems that make up the system based on the results of safety analysis, and the standards EN50128 and EN50129 respectively define the design criteria to be applied to software and hardware components based on the SIL levels assigned based on the results of safety analysis.

[0004] The following is known from the prior art. - Safety calculations related to the emergency braking function implemented according to the European standard EN50126 systematically assign a safety level SIL, SIL≧3, to the emergency braking function and thus to the subsystems that implement them. - Safety calculations related to the service braking function implemented according to the European standard EN50126 usually assign a safety level SIL≦2 to the service braking function and thus to the subsystems that implement them. - The development of a microprocessor-based or FPGA-based control unit compliant with safety integrity level SIL≧3 according to EN50128 and EN50129 requires design, verification, and certification costs that are approximately one order of magnitude higher than those for a design compliant with a safety integrity level of SIL≦2.

[0005] Regarding the last point mentioned above, it is clear that the functions to be developed according to a safety level of SIL≧3 should be extremely limited and simple.

[0006] Figure 1 shows a pneumatic brake actuator 100 according to the prior art. The mechanical assembly 101 is known to those skilled in the art as a slack adjuster.

[0007] Due to continuous braking, the pads and the disk continuously wear over time. Therefore, the free play of the brake actuator increases over time, resulting in a greater delay when applying the brake.

[0008] The purpose of the slack adjuster is to maintain a constant static distance between the braking surface of the brake pad and the surface of the disk in the non-braking state because the thickness of the brake pad and the disk continuously decreases due to wear caused by braking. In this way, the delay when applying the brake due to the free play of the lever is maintained constant over time, so that in the case of an emergency brake in particular, the braking time or the stopping distance of the vehicle or train can be accurately calculated.

[0009] It is well known to those skilled in the art that the free play of the brake actuator lever at the attachment between the lever and the brake cylinder is defined as a "dimension A" which is the distance "A" hereinafter.

[0010] For reference, dimension A has a typical value of 2 mm for a disk actuator and a typical value of 6 mm for a wheel actuator.

[0011] In the case of a shoe brake device, the same shoe and wheel wear adjustment mechanism is applied.

[0012] It is clear that the functional complexity of the mechanical assembly 101 involves the complexity resulting from assembly and testing, as well as the final cost.

[0013] Unfortunately, in the conventional brake actuator, the procedure for resetting the initial distance A is manually performed by the operator tasked with replacing the friction means of the brake force applying means 217 every time the friction means is replaced, and special attention and tools are required.

[0014] FIG. 2 shows a functional block diagram of an electromechanical brake actuator 200 according to the prior art.

[0015] The electromechanical module 201 includes at least one electric motor and, optionally, a speed reducer, i.e., a torque multiplier, and can extend and retract a force transmission member (i.e., arm 206) connected to the emergency brake module 207.

[0016] The emergency brake module 207 includes emergency brake energy storage means 208, for example, a mechanical storage element of mechanical position energy or kinetic energy.

[0017] Essentially, the emergency brake module 207 is controlled by an electric signal 210 and is configured to be able to take a first state in which it does not release the stored energy for executing an emergency brake when the emergency brake request signal 210 does not indicate the necessity of an emergency brake request. Further, the emergency brake module 207 controlled by the electric signal 210 is configured to be able to take a second state in which it releases the stored energy for executing an emergency brake when the emergency brake request signal 210 indicates the presence of an emergency brake request and thus the necessity of executing an emergency brake.

[0018] For the purposes of the present invention, a more detailed description of the operation of the emergency brake module 207 is not necessary.

[0019] Another force transmission member (i.e., arm 211) is connected to force sensor means 212 configured to generate a brake force indicating electrical signal 213 which is a value indicative of the mechanical force applied between the force transmission member 211 and yet another force transmission member (i.e., arm 216).

[0020] The brake force indicating electrical signal 213 is input to the service brake control unit 202.

[0021] The arm 216 is connected to the force sensor means 212 and the brake force applying means 217.

[0022] The brake force applying means 217 is schematically represented, by way of example, by envisioning a brake device / actuator having brake shoes on the wheels, although the brake force applying means 217 may be of other forms, such as a lever brake device / actuator having pads on a disk, for example.

[0023] The electronically configured service brake control unit 202 may receive, at its input, a power supply signal 205 conveying a power supply voltage not limited in origin to the vehicle's battery.

[0024] The service brake control unit 202 is configured to modulate the power supply voltage and control an electric motor included in the electromechanical module 201 via at least one electric brake force control signal 204.

[0025] The service brake control unit 202 receives, as an input, at least one angular position signal 219 which is not limited to indicating the angular position and direction of rotation of a rotating member present within the electromechanical module 201.

[0026] In a possible non-limiting embodiment, at least one angular position signal 219 includes an angular position signal generated by a hall sensor belonging to a BLDC type motor.

[0027] Through the counting integration method executed by the service brake control unit 202, the service brake control unit 202 continuously obtains the instantaneous elongation amount of the arm 206 over time, that is, the position of the braking force applying means 217.

[0028] In other possible embodiments, the position sensor means 220 (for example, a position sensor) continuously indicates its instantaneous elongation amount to the service brake control unit 202 over time via the electrical position signal 221, that is, reads the translational position of the arm 206 indicating the position of the braking force applying means 217.

[0029] The figure shown in FIG. 3 shows the relationship between the position P of the arm 206 and the force F applied by the braking force applying means 217.

[0030] Taking the initial position of the arm 206 corresponding to the horizontal axis value P = -A, that is, the static position corresponding to the distance A, the applied force F has a null value with respect to the total distance covered by the arm 206 from the horizontal axis values -A and 0 corresponding to the initial contact point between the braking force applying means 217 and the braking force receiving means (dissipating means), that is, the brake disc in the case of a disc brake or the wheel in the case of a wheel brake.

[0031] The positive position value P corresponds to the positive force value F applied by the braking force applying means 217.

[0032] The angular coefficient of segment E represents the elasticity of the braking force applying means 217. The greater the elasticity, the smaller the angular coefficient.

[0033] Here, when the actuator applies a braking force F' corresponding to the position P', in response to a request to cancel the braking force, the service brake control unit 202 commands the electromechanical module 201 to retract the arm 206 at a predetermined speed.

[0034] At the same time, the service brake control unit 202 receives the value of the position of the arm 206 by counting and integrating the rotation of the rotating member of the electromechanical module 201 via the position signal 221, that is, via at least one angular position signal 219.

[0035] When the braking force indication electrical signal 213 indicating the value F of the applied force reaches a null value, the service brake control unit 202 continues to command the electromechanical module 201 to retract the arm 206 until it reaches position -A.

[0036] In this way, the wear received by the shoe and the wheel is corrected each time the brake is applied.

[0037] The restored dimensional resolution corresponds to the measurement resolution of the arm position 206 by the method described above.

[0038] The described solution advantageously removes the complex mechanical assembly 101 known as a scrap adjuster by a simple software procedure executed by the service brake control unit 202 each time the service brake is released.

[0039] A method similar to that reported as the prior art described so far is claimed in European Patent EP3346155.

[0040] The service brake control unit 202 is conventionally developed in accordance with safety level SIL≦2 with respect to standards EN50128 and EN50129.

[0041] In this case, malfunctions of the software function that controls the recovery of distance A may occur with a probability specific to a SIL safety level ≤ 2.

[0042] Since the software is the same for all brake actuators in the train, the software needs to be considered as a common mode failure source, that is, it can be regarded as a failure occurring simultaneously throughout the train.

[0043] Malfunctions of the software function that controls the adjustment of distance A may appear in a form where the arm 206 is continuously retracted to the maintenance position -B (travel end position) corresponding to the position required for the maintenance of the braking force applying means 217 and does not stop at point -A in the figure of FIG. 3. The maintenance of the braking force applying means 217 may require, for example, the replacement of the friction means of the braking force applying means 217.

[0044] Position -B can be several tens of millimeters, which is orders of magnitude larger than position -A.

[0045] In this case, the delay in brake application can reach a value of several seconds.

[0046] When an emergency brake is required after a software anomaly occurs in a common mode across the entire line, at the standard speed of 160 km / h of a regional train, the stopping distance increases by approximately 44 m for each 1 - second delay.

[0047] From this consideration, the software function that controls the recovery of distance A, and the hardware on which it is executed, must be developed to the same safety level as the emergency brake, that is, it is concluded that the service brake control unit 202 should be fully developed to a SIL level ≥ 3 in accordance with the standards EN50128 and EN50129.

[0048] Unfortunately, this requirement is already very complex in the current solution compliant with a safety level of SIL ≤ 2 and has a significant impact on the development and manufacturing costs of the service brake control unit.

Summary of the Invention

[0049] Therefore, an object of the present invention is to provide an electromechanical brake actuator for a vehicle, in particular for at least one railway vehicle, which can prevent improper conduction of the brake force applying means in the maintenance position.

[0050] Accordingly, another object of the present invention is to provide an electromechanical brake actuator for a vehicle, in particular for at least one railway vehicle, which is implemented by software means while maintaining all safety requirements compatible with the latest emergency brakes, and the electromechanical brake actuator, in some embodiments, restores the wear of the distance A, i.e., the shoe and wheel or pad and disk.

[0051] Yet another object of the present invention is to provide an electromechanical brake actuator having a procedure for safely maintaining the brake force applying means.

[0052] The above and other objects and advantages are achieved, according to one aspect of the present invention, by an electromechanical brake actuator for a vehicle, in particular for a vehicle having the features defined in claim 1, in particular for at least one railway vehicle, by an electromechanical brake actuator for a vehicle having the features defined in claim 9, in particular for at least one railway vehicle, and by a brake system having the features defined in claim 25.

[0053] Preferred embodiments of the present invention are defined in the dependent claims, the content of which should be understood as an essential part of this specification.

Brief Description of the Drawings

[0054] Next, the functional and structural features of some preferred embodiments of the electromechanical brake actuator for a vehicle, in particular for at least one railway vehicle, according to the present invention will be described. Refer to the following attached drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0055] Before describing in detail the embodiments of the present invention, it should be made clear that the present invention is not limited to the details of the construction and configuration of the components shown in the following description or in the drawings. The present invention contemplates other embodiments and can actually be implemented or constructed in different ways. Also, it should be understood that the expressions and terms are for descriptive purposes and should not be construed as limiting. The use of "include" and "comprise" and their variations should be understood to include the components described below and their equivalents, as well as additional components and their equivalents.

[0056] In a first embodiment, an electromechanical brake actuator 400 for at least one vehicle, particularly for at least one railway vehicle, according to the present invention comprises a service brake control unit 202 configured to receive a service brake force demand electrical signal 203 and generate a brake force control signal 204 whose value is a function of the service brake force demand electrical signal 203.

[0057] Furthermore, the electromechanical actuator 400 includes an electromechanical module 201 configured to receive a brake force control signal 204 generated by the service brake control unit 202 and generate a brake force whose value is a function of the brake force control signal 204. Also, the electromechanical module 201 is configured to receive power via the brake force control signal 204. In this case, the signal 204 can be considered as a power and power control signal.

[0058] In addition, the electromechanical actuator 400 includes at least one force transmission member 206, 211, 216 configured to transmit the brake force generated by the electromechanical module 201 to the brake force applying means 217. The at least one force transmission member 206, 211, 216 is configured to be controlled by the electromechanical module 201 to translate along the translation axis Xt. When the at least one force transmission member 206, 211, 216 is translated in the first application direction, the brake force applied by the brake force applying means 217 increases, and when the at least one force transmission member 206, 211, 216 is translated in the second application direction opposite to the first application direction, the brake force applied by the brake force applying means 217 decreases.

[0059] Furthermore, the electromechanical actuator 400 includes a safety unit 401 configured as follows. - Receiving an electrical position signal whose value indicates the position of the brake force applying means 217 along the translation axis Xt, - Determining the instantaneous position of the brake force applying means 217 from the electrical position signal 221, - Preventing the brake force control signal 204 issued by the service brake control unit 202 from reaching the electromechanical module 201 via the first cutoff means 403 in the following cases. a) From the value of the electrical position signal 221, the safety unit 401 determines that the braking force applying means 217 is at a position along the force application axis Xb between the maintenance position at a first distance - B from the braking force receiving means and the rest position at a second distance - A smaller than the first distance - B from the braking force receiving means 218. b) The safety unit determines, based on the change over time of the electrical position signal 221, that the braking force applying means 217 is moving from the rest position to the maintenance position.

[0060] As can be understood, the translation axis Xt and the braking force application axis Xb may coincide, be parallel, or exist in different planes.

[0061] Preferably, the safety unit 401 may be configured to receive a maintenance request signal 222 configured to take a first value indicating that there is no need to set the braking force applying means 217 to the maintenance position and a second value indicating that the braking force applying means 217 needs to be set to the maintenance position. In this case, the safety unit 401 may be configured as follows. - Via a first blocking means 403, prevent the braking force control signal 204 issued by the service brake control unit 202 from reaching the electromechanical module 201 in the following cases. a) The maintenance request signal 222 takes its first value, and the safety unit 401 determines from the value of the electrical position signal 221 that the braking force applying means 217 is at a position along the braking force application axis Xb between the maintenance position and the rest position. b) The safety unit determines, based on the change over time of the electrical position signal 221, that the braking force applying means 217 is moving from the rest position to the maintenance position.

[0062] Preferably, the safety unit 401 is further configured to receive a maintenance verification signal 223 configured to take a first value indicating non - confirmation of permission to set the braking force applying means 217 to the maintenance position and a second value indicating confirmation of permission to set the braking force applying means 217 to the maintenance position. In this case, the safety unit 401 may be configured as follows. -Via the first blocking means 403, the brake force control signal 204 issued by the service brake control unit 202 is prevented from reaching the electromechanical module 201 in the following cases. a) Both the maintenance request signal 222 and the maintenance verification signal 223 take their respective first values, and the safety unit 401 determines from the value of the electrical position signal 221 that the brake force applying means 217 is at a position along the brake force application axis Xb between the maintenance position and the rest position. b) The safety unit determines, based on the change over time of the electrical position signal 221, that the brake force applying means 217 is moving from the rest position to the maintenance position.

[0063] Alternatively, or additionally, the safety unit 401 may be configured as follows. -Via the first blocking means 403, when the brake force control signal 204 issued by the service brake control unit 202 reaches the electromechanical module 201 when the maintenance request signal 222 and the maintenance verification signal 223 take different values from each other (i.e., non-matching values, for example, the maintenance request signal 222 takes its first value and the maintenance verification signal 223 does not take its first value, or the maintenance request signal 222 takes its second value and the maintenance verification signal 223 does not take its second value), and the safety unit 401 determines from the electrical position signal 221 that the brake force applying means 217 is at a position along the brake force application axis Xb between the maintenance position and the rest position.

[0064] Alternatively, or additionally, the safety unit 401 may be configured as follows. -Via the first blocking means 403, when both the maintenance request signal 222 and the maintenance verification signal 223 take their respective second values, and the safety unit 401 determines from the electrical position signal 221 that the brake force applying means 217 is at the rest position, the brake force control signal 204 issued by the service brake control unit 202 is allowed to reach the electromechanical module 201.

[0065] Furthermore, the safety unit 401 may be configured to prevent a brake force control signal 204 issued by the service brake control unit 202 from reaching the electromechanical module 201 via the first blocking means 403 in the following cases. - Both the maintenance request signal 222 and the maintenance verification signal 223 take their respective second values, - The safety unit 401 determines from the electrical position signal 221 that the brake force applying means 217 is in the maintenance position.

[0066] Preferably, the electromechanical brake actuator 400 may comprise force sensor means, such as a force sensor, configured to generate a brake force indicating electrical signal 213 which is a value indicating the value of the brake force generated by the electromechanical module 201. In an embodiment where only the maintenance request signal 222 is present, the service brake control unit 202 may then be configured to receive the brake force indicating electrical signal 213, when the brake force applying means 217 is in the maintenance position and the maintenance request signal 222 takes its first value, - The safety unit 401 is configured via the first blocking means 403 to allow the brake force control signal 204 issued by the service brake control unit 202 to reach the electromechanical module 201 again, - The service brake control unit 202 may be configured by the brake force control signal 204 to bring the brake force applying means 217 to a brake applying position in contact with the brake receiving means 218. In this case, the service brake control unit 202 is configured to determine that the brake force applying means 217 has reached the brake applying position when the brake force indicating electrical signal 213 changes from a null value to a non-null value (i.e., changes from a null value to a non-null value) after the brake force indicating electrical signal 213 has taken a null value, - When the brake force applying means 217 reaches the brake applying position in contact with the brake receiving means 218, the service brake control unit 202 may be configured via the brake force control signal 204 to bring the brake force applying means 217 from the predetermined brake applying position to a new rest position having a second distance - A again.

[0067] In an embodiment where both the maintenance request signal 222 and the maintenance verification signal 223 are present, when the braking force applying means 217 is in the maintenance position and both the maintenance request signal 222 and the maintenance verification signal 223 take their respective first values, - The safety unit 401 may be configured to allow the braking force control signal 204 issued by the service brake control unit 202 to reach the electromechanical module 201 again via the first cutoff means 403. - The service brake control unit 202 may be configured to set the braking force applying means 217 to the braking application position in contact with the braking force receiving means 218 via the braking force control signal 204. In this case, the service brake control unit 202 is configured to determine that the braking application position coincides with the position of the braking force applying means 217 when the braking force indicating electrical signal 213 changes from a null value to a non-null value (i.e., changes from a null value to a non-null value) after the braking force indicating electrical signal 213 has taken a null value. - When the braking force applying means 217 reaches the braking application position in contact with the braking force receiving means 218, the service brake control unit 202 may be configured to set the braking force applying means 217 to a new rest position having a second distance - A again from a predetermined braking application position via the braking force control signal 204.

[0068] Furthermore, when the braking force indicating electrical signal 213 changes from a non-null value to a null value again (i.e., changes from a non-null value to a null value) after taking a non-null value, the service brake control unit 202 may be configured to determine that the braking force applying means 217 is in the brake release position where it is no longer in contact with the braking force receiving means 218. The service brake control unit 202 may be configured to set the braking force applying means 217 to a new rest position having a second distance - A from a predetermined brake release position via the braking force control signal 204.

[0069] In the second embodiment, the electromechanical module 201 of the electromechanical brake actuator 400 for a vehicle, particularly for at least one railway vehicle, receives power supply via a special power supply signal 405 instead of receiving power supply via the brake force control signal 204.

[0070] In the above case, the safety unit 401 is configured via the first cutoff means 403' to prevent the power signal 405 from reaching the electromechanical module 201 in the following cases. a) From the value of the electrical position signal 221, the safety unit 401 determines that the brake force applying means 217 is at a position along the brake force application axis Xt between the service position of the first distance - B from the brake force receiving means and the rest position of the second distance - A smaller than the first distance - B from the brake force receiving means, b) The safety unit determines, based on the change over time of the value of the electrical position signal 221, that the brake force applying means 217 is moving from the rest position to the maintenance position.

[0071] Preferably, also for this second embodiment, the safety unit 401 may receive a maintenance request signal 222. In the above case, the safety unit 401 may be configured by the first cutoff means 403' to prevent the power signal 405 from reaching the electromechanical module 201 in the following cases. a) The safety unit 401 determines from the value of the electrical position signal 221 that the brake force applying means 217 is at a position along the brake force application axis Xt between the maintenance position and the rest position, b) The safety unit determines, based on the change over time of the value of the electrical position signal 221, that the brake force applying means 217 is moving from the rest position to the maintenance position.

[0072] Preferably, also for this second embodiment, the safety unit 401 may be configured to receive a maintenance verification signal 223. In the above case, the safety unit 401 may be configured by the first cutoff means 403' to prevent the power signal 405 from reaching the electromechanical module 201 in the following cases. a) Both the maintenance request signal 222 and the maintenance verification signal 223 take their respective first values, and the safety unit 401 determines from the value of the electrical position signal 221 that the braking force applying means 217 is at a position along the braking force application axis Xb between the maintenance position and the rest position. b) The safety unit determines, based on the change over time of the value of the electrical position signal 221, that the braking force applying means 217 is moving from the rest position to the maintenance position.

[0073] Alternatively, or in addition, the safety unit 401 may be configured as follows. - When the maintenance request signal 222 and the maintenance verification signal 223 take different values from each other (i.e., non - matching values, for example, the maintenance request signal 222 takes its first value and the maintenance verification signal 223 does not take its first value, or the maintenance request signal 222 takes its second value and the maintenance verification signal 223 does not take its second value) via the first blocking means 403', and the safety unit 401 determines from the electrical position signal 221 that the braking force applying means 217 is at a position along the braking force application axis Xb between the maintenance position and the rest position, prevent the power supply signal 405 from reaching the electromechanical module 201.

[0074] Alternatively, or in addition, the safety unit 401 may be configured as follows. - When both the maintenance request signal 222 and the maintenance verification signal 223 take their respective second values via the first blocking means 403', and the safety unit 401 determines from the electrical position signal 221 that the braking force applying means 217 is at the rest position, allow the power signal 405 to reach the electromechanical module 201.

[0075] Preferably, referring to the second embodiment, the safety unit 401 further prevents, via the second blocking means 406, the brake force control signal 204 issued by the service brake control unit 202 from reaching the electromechanical module 201 when the safety unit prevents the power signal 405 from reaching the electromechanical module 201 via the first blocking means 403'.

[0076] Also, in this second embodiment, the electromechanical actuator 400 may include force sensor means 212 configured to generate a brake force indicating electrical signal 213, which is a value indicating the value of the brake force generated by the electromechanical module 201. The service brake control unit may be configured to receive the brake force indicating electrical signal 213.

[0077] In the case where only the maintenance request signal 222 exists, the brake force applying means 217 is in the maintenance position, and when the maintenance request signal 222 takes its first value, - The safety unit 401 may be configured to allow the power signal 405 to reach the electromechanical module 201 again via the first blocking means 403'. - The service brake control unit 202 may be configured to set the brake force applying means 217 to the brake applying position in contact with the brake force receiving means 218 via the brake force control signal 204. The service brake control unit 202 is configured to determine that the brake force applying means 217 has reached the brake applying position when the brake force indicating electrical signal 213 takes a null value and then takes a null value after the brake force indicating electrical signal 213 has taken a null value. - When the brake force applying means 217 reaches the brake applying position in contact with the brake force receiving means 218, the service brake control unit 202 may be configured to set the brake force applying means 217 to a new rest position having a second distance - A again from the predetermined brake applying position via the brake force control signal 204.

[0078] In the case where both the maintenance request signal 222 and the maintenance verification signal 223 are present, the braking force applying means 217 is in the maintenance position, and when both the maintenance request signal 222 and the maintenance verification signal 223 take their respective first values, - The safety unit 401 may be configured to allow the power signal 405 to reach the electromechanical module 201 again via the first interrupting means 403'. - The service brake control unit 202 may be configured to set the braking force applying means 217 to a braking application position in contact with the braking force receiving means 218 via the braking force control signal 204. Here, the service brake control unit 202 is configured to determine that the braking application position coincides with the position where the braking force applying means 217 is located when the braking force indicating electrical signal 213 changes from a null value to a non-null value (i.e., changes from a null value to a non-null value) after the braking force indicating electrical signal 213 has taken a null value. - When the braking force applying means 217 reaches the braking application position in contact with the braking force receiving means 218, the service brake control unit 202 may be configured to set the braking force applying means 217 to a new rest position having a second distance - A again from a predetermined braking application position via the braking force control signal 204.

[0079] In addition, when the braking force indicating electrical signal 213 takes a non-null value and then takes a null value again, the service brake control unit 202 may be configured to determine a brake release position where the braking force applying means 217 is no longer in contact with the braking force receiving means 218. It may be configured to set the braking force applying means 217 to a new rest position having a second distance - A again from a predetermined brake release position via the braking force control signal 204.

[0080] Furthermore, with respect to all of the above-described embodiments, the electrical position signal 221 may be generated by position sensor means 220 configured to measure the position of at least one of the force transmission members 206, 211, 216 along the translation axis Xt. Additionally, the electromechanical module 201 may include at least one rotating mechanical member, and the electrical position signal 221 may be generated by angular position sensor means configured to measure the angular position and the direction of rotation of at least one rotating member of the electromechanical module 201.

[0081] Furthermore, referring to all of the above-described embodiments, the electromechanical actuator 400 may include an emergency brake module 207 including emergency brake energy storage means 208 configured to store energy used for at least one emergency brake. In this case, the emergency brake module 207 may take a first state in which, when the emergency brake request signal 210 is received and does not take a value indicating the need to execute an emergency brake, the stored energy is not released to the emergency brake storage means 208, and a second state in which, when the emergency brake request signal 210 takes a value indicating the need to execute an emergency brake, the stored energy is released to the emergency brake storage means 208.

[0082] Furthermore, referring to all of the above-described embodiments, the safety unit 401 may be developed according to a safety level SIL higher than the safety level SIL at which the service brake control unit 202 is developed. Additionally, the safety unit 401 may be developed according to a safety level SIL ≧ 3. Furthermore, the safety unit 401 may include a microprocessor and / or an FPGA.

[0083] Hereinafter, with reference to FIG. 4, the operation of the brake actuator 400 will be described in detail with reference to an embodiment in which, in other words, the electromechanical module 201 receives power via the brake force control signal 204.

[0084] In this first exemplary embodiment, the electromechanical brake actuator 400 is provided for both service and emergency braking.

[0085] The electromechanical brake actuator 400 includes an electromechanical module 201 configured to receive a brake force control signal 204 and generate a first brake force that generates a brake force whose value is a function of the brake force control signal 204.

[0086] The electromechanical module 201 may include, for example, an electric motor 230 that is not limitedly connected to a mechanical speed reducer 231. Additionally, the electromechanical module 201 may include a mechanical conversion member 232 that converts rotational motion into translational motion. The mechanical conversion member 232 that converts rotational motion into translational motion may be directly driven by the electric motor 230 or, in some cases, may be driven by the mechanical speed reducer 231. The mechanical conversion member 232 that converts rotational motion into translational motion may be configured to transmit a brake force to a plurality of force transmission members 206, 211, 216 configured to transmit the brake force from the electromechanical module 201 to the brake force applying means 217. The brake force applying means 217 may be at least one brake force applying device 217.

[0087] Along the mechanical force transmission chain, there may be an emergency brake module 207 including an emergency brake energy storage means 208 such as, for example, a mechanical tensile energy storage element or a kinetic energy storage element.

[0088] Essentially, the emergency brake module 207 is controlled by an electric emergency brake request signal 210 and has a first state in which when the electric emergency brake request signal 210 does not indicate a request for an emergency brake, the energy stored in the emergency brake energy storage means 208 is not released for the emergency brake, and a second state in which when the electric emergency brake request signal 210 indicates a request for an emergency brake, the energy stored in the emergency brake energy storage means 208 is released to apply an emergency brake.

[0089] The electromechanical module 201 may be configured to generate at least an angular position signal 219 indicating a value of an angular position of one of the rotating elements included in the electromechanical module.

[0090] When the electric motor 230 is a BLDC type electric motor, at least one angular position signal 219 indicating a value of the angular position may not be composed only of signals generated by the hall sensors of the BLDC type electric motor 230.

[0091] Alternatively, and without limitation, at least one angular position signal 219 indicating a value of an angular position of one of the rotating elements included in the electromechanical module 201 may be composed of signals generated by a magnetic sensor indicating an amount and a direction of rotation of one of the rotating mechanical elements included in the electromechanical module 201.

[0092] Furthermore, referring to FIG. 4, the electromechanical brake actuator 400 may further include force sensor means 212 configured to measure a braking force generated by the electromechanical module 201 and generate a braking force indicating electrical signal 213. The value of the braking force indicating electrical signal 213 indicates a value of a first braking force. The force sensor means may be, for example, a load cell type force sensor.

[0093] Furthermore, the electromechanical brake actuator 400 may include position sensor means 220 configured to measure a translational position of force transmission members 206, 211, 216 configured to transmit a braking force from the electromechanical module 201 to the braking force applying means 217, but is not limited thereto. The position sensor means 220 is further configured to generate an electrical position signal 221.

[0094] The value of the electrical position signal 221 indicates the translational position of the braking force applying means 217.

[0095] The position sensor means 220 may be, for example, an optical linear position sensor, an LVDT linear transformer, or a magnetic linear position sensor.

[0096] Furthermore, the electromechanical brake actuator 400 may include a first service brake control unit 202 configured to receive at least the following. - Service brake force demand electrical signal 203 - Power supply 205 - Brake force indication electrical signal 213 - Electrical position signal 221 indicating the translational position of the brake force applying means 217 - Angular position electrical signal 219 indicating the angular position of one of the rotating components constituting the electromechanical module 201 - Maintenance request signal 222 indicating the need to replace the friction means of the brake force applying means 217, having a first state that does not indicate a request to set the brake force applying means 217 to the maintenance position - B, and a second state that indicates a request to set the brake force applying means 217 to the maintenance position - B and facilitates the maintenance of the brake force applying means - Maintenance verification signal 223 indicating the verification of the need to replace the brake force applying means 217, having a first state that does not confirm permission to set the brake force applying means 217 to the maintenance position - B, and a second state that confirms permission to set the brake force applying means 217 to the maintenance position - B

[0097] The service brake control unit 202 may further be configured to control the electromechanical module 201 via the brake force control signal 204 to generate a brake force having a value corresponding to, i.e., a function of, the value of the service brake force demand signal 203.

[0098] Furthermore, the service brake control unit 202 may be configured to integrate the change in the angular position indicated by the angular position signal 219 and perform a calculation to convert it into the value of the translational position of the force transmission means 206, 211, 216 configured to transmit the brake force from the electromechanical module 201 to the brake force applying means 217.

[0099] While the service brake is applied, if the service brake control unit 202 receives a request to reset the service brake force, the service brake control unit 202 reduces the brake force by continuously monitoring the value of the force indicated by the brake force indication electrical signal 213.

[0100] When the brake force indication electrical signal 213 indicating the value of the brake force indicates the value of the null brake force, the service brake control unit 202 is configured as follows. - Store the translational position of the brake force applying means 217 as the "zero" reference point for measuring the stationary distance - A, - Command the electromechanical module 201 by at least one brake force control signal 204 to maintain a predetermined rotational speed without changing the rotational direction of the electric motor, - Continuously monitor the variation of the translational position of the brake force applying means 217, where the translational position is obtained by the electrical position signal 221 indicating the translational position of the brake force applying means 217, and alternatively, by integrating the variation of the angular position indicated by the angular position signal 219 related to one of the rotating mechanical members included in the electromechanical module 201 and performing an operation to convert the variation of the angular position into the value of the translational position of the brake force applying means 217, - When the translational position of the brake force applying means 217 reaches the distance - A within a predetermined allowable range with respect to the "zero" reference point stored in the first step, command the electromechanical module 201 to a predetermined rest position, that is, to stop rotating since the distance - A has been reached.

[0101] Also, when the translational position of the brake force applying means 217 reaches the distance - A, the service brake control unit 202 is configured as follows. - Continuously monitor the states of the maintenance request signal 222 and the maintenance verification signal 223, -When in the first state where the maintenance request signal 222 does not present a request to move the braking force applying means 217 to the maintenance position -B, or when in the first state where the maintenance verification signal 223 does not confirm permission to move the braking force applying means 217 to the maintenance position -B, the service brake control unit 202 does not execute any operation via signal 203 until a new braking force request arrives. -When the maintenance request signal 222 takes the second state of presenting a request to move the braking force applying means 217 to the maintenance position -B, and at the same time the maintenance verification signal 223 takes the second state of confirming permission to move the braking force applying means 217 to the maintenance position -B, the service brake control unit 202 commands the electromechanical module 201 to move the braking force applying means 217 to the maintenance position -B, enabling, for example, an operator tasked with maintaining the braking force applying means to replace the friction means of the braking force applying means. -From the previous state, that is, when the braking force applying means 217 is in the maintenance position -B, when the maintenance request signal 222 takes the first state of not presenting a request to move the braking force applying means 217 to the maintenance position -B, and when the maintenance verification signal 223 takes the first state of not confirming permission to move the braking force applying means 217 to the maintenance position -B, the service brake control unit 202 commands the electromechanical module 201 to bring the braking force applying means 217 into contact with the disc in the case of a disc brake or with the wheel in the case of a wheel brake.

[0102] The moment the braking force indication signal 213 indicates a braking force value greater than the null value, that is, the moment it indicates that the braking force applying means 217 has come into contact with the disc in the case of a disc brake or with the wheel in the case of a wheel brake, the service brake control unit 202 executes the aforementioned confirmation again to reach the rest position -A.

[0103] Therefore, the electromechanical actuator 400 accurately resets the position of the braking force applying means 217 after the maintenance of the braking force applying means 217.

[0104] The electromechanical brake actuator 400 further comprises a safety unit 401 configured to receive at least the following. - Brake force indicating electrical signal 213 - Electrical position signal 221 indicating the translational position of the translational position of the brake force applying means 217 - Electrical angular position signal 219 indicating the angular position of one of the rotating members of the electromechanical module 201 - Maintenance request signal 222 for the maintenance requirements of the friction means of the brake force applying means 217 - Maintenance verification signal 223

[0105] The service brake control unit 202 is configured to perform an operation of integrating the change in the angular position indicated by the angular position signal 219 and convert it into the value of the translational position of the force transmission members 206, 211, 216 configured to transmit the brake force from the electromechanical module 201 to the brake force applying means 217.

[0106] In the example of FIG. 4, the safety unit 401 is configured to generate a control signal 402 for controlling a first cutoff means 403 (for example, a cutoff device such as a control switch, relay) to cutoff or not cutoff the brake force control signal 204 that also supplies power.

[0107] When both the power signal 405 and the brake force control signal 204 are present, referring to the example of FIG. 5, the safety unit 401 may be configured to generate a control signal 402 for controlling a first cutoff means 403' that cutoff or does not cutoff the power signal 405 and / or a second cutoff means 406 (for example, a cutoff device such as a control switch, relay) that cutoff or does not cutoff the brake force control signal 204.

[0108] When the braking force control signal 204 supplies power to the electromechanical module 201, the first cutoff means 403 is configured to allow the service brake control unit to supply power to and control the electromechanical module 201 via at least one braking force control signal 204 when the control signal 402 does not command the cutoff of control and power to the electromechanical module 201. Further, when the control signal 402 commands the cutoff of control and power to the electromechanical module 201, the first cutoff means 403, at the moment of cutoff of at least one control signal 204, forces the electromechanical module 201 to maintain the transmission member 206 at its current position, thereby preventing the service brake control unit from supplying power to and controlling the electromechanical module 201 via at least one control signal 204.

[0109] When a power signal 405 exists, for example, referring to FIG. 5, the first cutoff means 403' is configured to supply power to the electromechanical module 201 via the power signal 405 when the first control signal 402 does not command the cutoff of power to the electromechanical module 201, and to cutoff the power from the power signal 405 to the electromechanical module 201 when the first control signal 402 commands the cutoff of power to the electromechanical module 201, and to force the electromechanical module 201 to maintain the transmission arm 206 at the current position at the moment of cutoff of at least one control signal and power signal 204.

[0110] In other words, by controlling the signal 402, the safety unit 401 may allow or prevent the control of the electromechanical module 201 by the service brake control unit 202.

[0111] The safety unit 401 may continuously monitor the braking force indication signal 213. At the moment when the braking force indication signal 213 changes from a force value greater than zero and a braking force value of zero, the safety unit 401 executes the following steps. - Store the value of the translational position of the braking force applying means 217 as the "zero" reference point for measuring the rest distance - A. - Continuously monitor the variation in the translational position of the braking force applying means 217. The translational position is obtained by the electrical position signal 221 indicating the translational position of the braking force applying means 217. Alternatively, the translational position is obtained by integrating the variation in the angular position indicated by the angular position signal 219 related to one of the rotating machine components included in the electromechanical module 201 and performing an operation to convert the variation in the angular position into the value of the translational position of the braking force applying means 217. - Continuously monitor the states of the maintenance request signal 222 and the maintenance verification signal 223. - When the translational position of the braking force applying means 217 reaches distance - A and then exceeds the absolute value by advancing to distance - B, at that time, if the maintenance request signal 222 is in the first state where it does not present a request to move the braking force applying means 217 to distance - B, or if the maintenance verification signal 223 is in the first state where it does not confirm permission to move the braking force applying means 217 to position - B, the safety unit 401 acts on the signal 402 to cut off the control signal 204 for the electromechanical module 201 (in an embodiment where the braking force control signal 204 is supplied to the electromechanical module 201), or cut off the power signal 405 for the electromechanical module 201 (in an embodiment where the power signal 405 supplies power to the electromechanical module 201). Switch the first cutoff means 403' to a state where the electromechanical module 201 is made to maintain the transmission arm 206 in a position close to distance - A, but is prepared to apply an emergency brake. Further, the safety unit 401 transmits an error indication via the error signal 404. - When the translational position of the braking force applying means 217 reaches the maintenance position - A and then exceeds the absolute value by advancing the distance - B, at the same time, when the maintenance request signal 222 takes a second state presenting a request to move the braking force applying means 217 by the distance - B and the maintenance verification signal 223 takes a second state confirming permission to move the braking force applying means 217 to the maintenance position - B, the safety unit 401 does not execute any operation, and the service brake control unit 202 commands the total movement amount of the braking force applying means 217, allowing the braking force applying means 217 to take the maintenance position - B necessary for the maintenance of the braking force applying means 217, such as the replacement of the friction means of the braking force applying means 217. When the maintenance position - B is reached, the safety unit 401 acts on the signal 402 to switch the first shut-off means to a state of shutting off the brake control signal 204 for the electromechanical module 201 (in the embodiment where the braking force control signal 204 supplies power to the electromechanical module 201), or the power signal 405 for the electromechanical module 201 (in the embodiment where the power signal 405 supplies power to the electromechanical module 201), allowing the electromechanical module 201 to maintain the transmission arm 206 at the maintenance position - B, allowing the maintenance operator to operate safely, and protecting against sudden inappropriate movement of the braking force applying means 217, - When, from the previous state, the maintenance request signal 222 takes a first state presenting no request to move the braking force applying means 217 to the maintenance position - B and the maintenance verification signal 223 takes a first state confirming no permission to move the braking force applying means 217 to the maintenance position - B, the safety unit 401 acts on the signal 402 to switch the first shut-off means 403 to a state of not shutting off the control power signal 204 for the electromechanical module 201 (in the embodiment where the braking force control signal 204 supplies power to the electromechanical module 201), or not shutting off the power signal 405 for the electromechanical module 201 (in the embodiment where the power signal 405 supplies power to the electromechanical module 201), and according to the above control, allowing the service brake force control module 202 to recover the rest position - A.

[0112] When the power signal 405 is supplied to the electromechanical module 201, a second cutoff means 406 may be provided that cuts off the brake force control signal 204 when the power signal 405 is cutoff.

[0113] It is clear that the safety unit 401 performs simple monitoring, cutoff, and alarm functions, and as a result, is much simpler in terms of implementation than the service brake control unit 202.

[0114] Therefore, it is preferable to develop the safety unit 401 with a SIL level higher than the SIL level at which the service brake control unit 202 was developed, that is, a SIL level consistent with the application of the emergency brake, and to develop the necessary safety requirements so that maintenance workers can safely operate the actuator for maintenance of the braking force applying means 217, such as the replacement of the friction means of the braking force applying means 217.

[0115] As described above, it is known from the prior art that safety analysis performed in accordance with the standard EN50126 recommends the application of a safety level SIL ≦ 2 for the development of HW - SW control units for service brakes of railway vehicles.

[0116] Developing the safety unit to a SIL ≧ 3 level advantageously results in a much lower development cost than developing a complete service brake control unit executed according to a SIL ≧ 3 safety level, a complete regeneration function due to the consumption of the friction material, and a function of maintaining the friction material at the same SIL ≧ 3 level.

[0117] In order to maintain the safety level path as it is, it is recommended that the maintenance verification signal 223 be designed at a SIL safety level equal to the SIL safety level at which the safety unit 401 was developed.

[0118] Referring to FIG. 6, in a further aspect, the present invention relates to a braking system including a plurality of brake actuators 400 according to any of the above-described embodiments or examples. The braking system includes a control unit 500 connected to the plurality of brake actuators 400 via communication means 501 such as a wired or wireless communication network. The control unit is configured to receive the following. - A parking brake signal (502) indicating whether the parking brake is applied - At least one speed signal 503 indicating the vehicle speed - A maintenance signal 504 whose value indicates whether a maintenance cycle of the braking system is required

[0119] Also, the control unit 500 is configured as follows. - When the maintenance signal 504 takes a value indicating a maintenance requirement, the parking brake signal 502 takes a value indicating that the parking brake is applied, and the speed signal 503 takes a value indicating a zero vehicle speed, a maintenance requirement signal 222 having its second value to be transmitted to at least one of the electromechanical actuators 400 via the communication means 501 is generated. - When at least one of the maintenance signal 504 taking a value not indicating a maintenance requirement, the parking brake signal 502 taking a value indicating that the parking brake is not applied, and the speed signal 503 taking a value indicating a non-zero vehicle speed occurs, a maintenance requirement signal 222 having its first value to be transmitted to the plurality of electromechanical actuators 400 via the communication means 501 is generated.

[0120] Each electromechanical actuator 400 may include user interface means 503, via which a person engaged in performing maintenance on the brake force applying means 217 causes the maintenance verification signal 223 to take its second value, positions the brake force applying means 217 in a maintenance position, and when the maintenance of the brake force applying means 217 is completed as when the replacement of the friction means of the brake force applying means 217 is completed, causes the maintenance verification signal 223 to take its first value and positions the brake force applying means 217 in a rest position.

[0121] In other words, referring to FIG. 6, the braking system may comprise a plurality of actuators 400 as described above, managed by a centralized brake control unit 500 provided for the safe execution of the maintenance cycle of the friction material.

[0122] The plurality of electromechanical actuators 400 may be connected to the braking system control unit 500 via communication means 501. The braking system control unit 500 may be configured to receive a signal 502 indicating that the parking brake is applied, at least one signal 503 indicating the vehicle speed, and a signal 504 indicating a request to execute a maintenance cycle for the braking system.

[0123] The braking system control unit 500 is configured to generate a maintenance request signal 222 requesting maintenance of the friction means of the braking force applying means 217 in a second state where the braking system maintenance request signal 504 indicating a request to execute a maintenance cycle for the system brake takes on a state indicating a request to execute the braking system maintenance cycle, the signal 502 indicating that the parking brake is applied indicates the parking brake applied to the train, and the vehicle speed signal 503 indicates a null speed, and presents a request to facilitate the replacement of the friction means, with the braking force applying means 217 in the maintenance position -B.

[0124] Each electromechanical actuator 400 may comprise a user interface 503, via which an operator tasked with performing maintenance on the braking force applying means 217, such as replacing the friction means, may also use the maintenance verification signal 223 as its second state to confirm permission to place the braking force applying means 217 in the maintenance position -B.

[0125] The user interface 503 may comprise, without limitation, an interface for computing means, and the interface may be configured to issue the maintenance verification signal 223 in its second state to confirm permission to place the braking force applying device 217 in the maintenance position -B in the presence of a predetermined safety code.

[0126] In its second state, in which the brake system control unit 500 presents a request to place the braking force applying means 217 in the maintenance position -B, but only for one electromechanical actuator 400 at a time, the brake system control unit 500 is configured to generate a maintenance request signal 222.

[0127] In this way, the system ensures that only one actuator 400 at a time can be placed in a maintenance state by the brake system control unit 500, for example for the replacement of the friction material of the braking force applying means 217, and that only the local consent of the operator, via the use of the local user interface 503, will reliably bring the individual electromechanical actuator 400 sent for maintenance into a state in which the braking force applying means 217 is placed in the maintenance position -B.

[0128] In addition, upon reaching the maintenance position -B, only the operator's action of removing the key from the user interface 505 allows the actuator 400 in the maintenance state to bring the braking force applying device 217 closer to the disc or wheel, ensuring that the operator can operate safely.

[0129] What has been described above with respect to the field of railway vehicles or railway trains may find similar applications in other fields, such as, for example, the field of general vehicles, vehicles with rubber tires, or escort vehicles with rubber tires.

[0130] Various aspects and embodiments of an electromechanical brake actuator and a brake system for a vehicle, in particular for at least one railway vehicle, according to the present invention have been described. It should be understood that each embodiment can be combined with any other embodiment. Furthermore, the present invention is not limited to the described embodiments and may be modified within the scope defined by the appended claims.

Claims

1. An electromechanical brake actuator (400) for a vehicle, in particular for at least one railway vehicle, comprising: - A service brake control unit (202) configured to receive a service brake force demand electrical signal (203) and generate a brake force control signal (204) whose value is a function of the service brake force demand electrical signal (203); - An electromechanical module (201) configured to receive the brake force control signal (204) generated by the service brake control unit (202) and generate a brake force whose value is a function of the brake force control signal (204), wherein the electromechanical module (201) is configured to also receive power via the brake force control signal (204); - At least one force transmission member (206, 211, 216) configured to transmit the brake force generated by the electromechanical module (201) to a brake force application means (217), the at least one force transmission member (206, 211, 216) being configured to be controlled by the electromechanical module (201) such that it translates along a translation axis (Xt), and the translation of the at least one force transmission member (206, 211, 216) in a first application direction is accompanied by an increase in the brake force applied by the brake force application means (217), and the translation of the at least one force transmission member (206, 211, 216) in a second application direction opposite to the first application direction is accompanied by a reduction in the brake force applied by the brake force application means (217); The electromechanical brake actuator (400) is characterized in that it comprises a safety unit (401) configured as follows: - Receiving an electrical position signal (221) whose value indicates the position of the brake force application means (217) along the translation axis (Xt); - Determining the instantaneous position of the brake force application means (217) based on the value of the electrical position signal (221); - Preventing the brake force control signal (204) issued by the service brake control unit (202) from reaching the electromechanical module (201) via a first cut-off means (403) in the following cases: a) Based on the value of the electrical position signal (221), the safety unit (401) determines that the braking force applying means (217) is at a maintenance position at a first distance (-B) from the braking force receiving means (218), and at a position along the braking force application axis (Xb) between the maintenance position and a rest position at a second distance (-A) from the braking force receiving means (218) that is smaller than the first distance (-B). b) Based on the change over time of the value of the electrical position signal (221), the safety unit determines that the braking force applying means (217) is moving from the rest position to the maintenance position. An electromechanical brake actuator (400), characterized by the above. **Claim 2** The safety unit (401) is configured to receive a maintenance request signal (222) that takes a first value indicating that there is no need to place the braking force applying means (217) in the maintenance position, and takes a second value indicating the need to place the braking force applying means (217) in the maintenance position. The safety unit (401) is also configured as follows: - Through the first cut-off means (403), the braking force control signal (204) issued by the service brake control unit (202) is prevented from reaching the electromechanical module (201) in the following cases: a) The maintenance request signal (222) takes its first value, and the safety unit (401) determines, based on the value of the electrical position signal (221), that the braking force applying means (217) is at a position along the braking force application axis (Xb) between the maintenance position and the rest position. b) Based on the change over time of the electrical position signal (221), the safety unit determines that the braking force applying means (217) is moving from the rest position to the maintenance position. The electromechanical brake actuator (400) according to Claim 1. **Claim 3** The safety unit (401) further receives a maintenance verification signal (223) that takes a first value indicating non-confirmation of permission to place the braking force applying means (217) in the maintenance position, and takes a second value indicating confirmation of permission to place the braking force applying means (217) in the maintenance position. The safety unit (401) is configured as follows: - via the first shut-off means (403), the brake force control signal (204) issued by the service brake control unit (202) is prevented from reaching the electromechanical module (201) when a) both the maintenance request signal (222) and the maintenance verification signal (223) take their respective first values, and the safety unit (401) determines, based on the value of the electrical position signal (221), that the brake force applying means (217) is at a position along the brake force application axis (Xb) between the maintenance position and the rest position; b) based on the change over time of the electrical position signal (221), the safety unit determines that the brake force applying means (217) is moving from the rest position to the maintenance position; and / or the safety unit (401) is configured as follows - via the first shut-off means (403), the brake force control signal (204) issued by the service brake control unit (202) is prevented from reaching the electromechanical module (201) when a) the maintenance request signal (222) takes its first value and the maintenance verification signal (223) does not take its first value, or the maintenance request signal (222) takes its second value and the maintenance verification signal (223) takes its second value; b) the safety unit (401) determines, based on the value of the electrical position signal (221), that the brake force applying means (217) is at a position along the brake force application axis (Xb) between the maintenance position and the rest position; and / or the safety unit (401) is configured as follows - via the first shut-off means (403), when both the maintenance request signal (222) and the maintenance verification signal (223) take their respective second values and the safety unit (401) determines, based on the value of the electrical position signal (221), that the brake force applying means (217) is at the rest position, the brake force control signal (204) issued by the service brake control unit (202) is allowed to reach the electromechanical module (201); The electromechanical brake actuator (400) according to claim 2.

4. The safety unit (401) is configured to prevent the brake force control signal (204) issued by the service brake control unit (202) from reaching the electromechanical module (201) via the first cutoff means (403) when: - both the maintenance request signal (222) and the maintenance verification signal (223) take their respective second values, - the safety unit (401) determines, based on the value of the electrical position signal (221), that the brake force applying means (217) is in the maintenance position, The electromechanical brake actuator (400) according to claim 3.

5. Comprising force sensor means (212) configured to generate a brake force indicating electrical signal (213) which is a value indicating the value of the brake force generated by the electromechanical module (201), The service brake control unit (202) is configured to receive the brake force indicating electrical signal (213). The electromechanical brake actuator (400) according to any one of claims 1 to 4.

6. When the brake force applying means (217) is in the maintenance position and the maintenance request signal (222) takes its first value: - the safety unit (401) is configured to allow the brake force control signal (204) issued by the service brake control unit (202) to reach the electromechanical module (201) again via the first cutoff means (403), - the service brake control unit (202) is configured, by the brake force control signal (204), to set the brake force applying means (217) to a brake applying position in contact with the brake receiving means (218), and the service brake control unit (202) is configured to determine that the brake force applying means (217) has reached the brake applying position when the brake force indicating electrical signal (213) takes a non-null value after taking a null value. - When the braking force applying means (217) reaches the braking application position in contact with the braking force receiving means (218), the service brake control unit (202) is configured to move the braking force applying means (217) from the braking application position to a new rest position having the second distance (-A) again via the braking force control signal (204). The electromechanical brake actuator (400) according to claim 5, which depends on claim 2. **Claim 7** When the braking force applying means (217) is in the maintenance position and both the maintenance request signal (222) and the maintenance verification signal (223) take their respective first values, - The safety unit (401) is configured to allow the braking force control signal (204) issued by the service brake control unit (202) to reach the electromechanical module (201) again via the first cutoff means (403). - The service brake control unit (202) is configured to set the braking force applying means (217) to the braking application position in contact with the braking force receiving means (218) by the braking force control signal (204). The service brake control unit (202) is configured to determine that the braking application position coincides with the position of the braking force applying means (217) when the braking force indicating electrical signal (213) takes a non-null value after taking a null value. - When the braking force applying means (217) reaches the braking application position in contact with the braking force receiving means (218), the service brake control unit (202) is configured to move the braking force applying means (217) from the predetermined braking application position to a new rest position having the second distance (-A) again via the braking force control signal (204). The electromechanical brake actuator (400) according to claim 5, which depends on claim 3 or claim 4. **Claim 8** When the braking force indicating electrical signal (213) takes a null value again after taking a non-null value, the service brake control unit (202) is configured to determine a brake release position where the braking force applying means (217) is no longer in contact with the braking force receiving means (218). The service brake control unit (202) configures the brake force applying means (217) to be a new rest position having the second distance (-A) again from the determined brake release position via the brake force control signal (204). The electromechanical brake actuator (400) according to any one of claims 5 to 7.

9. An electromechanical brake actuator (400) for a vehicle, particularly for at least one railway vehicle, comprising: - A service brake control unit (202) configured to receive a service brake force demand electrical signal (203) and generate a brake force control signal (204) whose value is a function of the service brake force demand electrical signal (203); - An electromechanical module (201) configured to receive the brake force control signal (204) generated by the service brake control unit (202) and generate a brake force whose value is a function of the brake force control signal (204), wherein the electromechanical module (201) is configured to receive power via a power signal (405); - At least one force transmission member (206, 211, 216) arranged to transmit the brake force generated by the electromechanical module (201) to the brake force applying means (217), wherein the at least one force transmission member (206, 211, 216) is arranged to be controlled by the electromechanical module (201) so as to translate along a translation axis (Xt), and the translation of the at least one force transmission member (206, 211, 216) in a first application direction is accompanied by an increase in the brake force applied by the brake force applying means (217), and the translation of the at least one force transmission member (206, 211, 216) in a second application direction opposite to the first application direction is accompanied by a reduction in the brake force applied by the brake force applying means (217); The electromechanical brake actuator (400) is characterized in that it comprises a safety unit (401) configured to receive an electrical position signal (221) having a value indicating the position of the brake force applying means (217) along the translation axis (Xt). The safety unit (401) is configured as follows: - Determine the instantaneous position of the braking force applying means (217) based on the value of the electrical position signal (221), - Prevent the power signal (405) from reaching the electromechanical module (201) via the first cutoff means (403') when a) Based on the value of the electrical position signal (221), the safety unit (401) determines that the braking force applying means (217) is at a position along the braking force application axis (Xb) between the maintenance position at a first distance (-B) from the braking force receiving means (218) and the rest position at a second distance (-A) smaller than the first distance (-B) from the braking force receiving means (218); b) Based on the change over time of the electrical position signal (221), the safety unit determines that the braking force applying means (217) is moving from the rest position to the maintenance position. An electromechanical brake actuator (400), characterized by the above.

10. The safety unit (401) also receives a maintenance request signal (222) configured to take a first value indicating that there is no need to set the braking force applying means (217) to the maintenance position and a second value indicating the need to set the braking force applying means (217) to the maintenance position. The safety unit (401) is configured as follows: - Prevent the power signal (405) from reaching the electromechanical module (201) via the first cutoff means (403') when a) The maintenance request signal (222) takes its first value and, based on the value of the electrical position signal (221), the safety unit (401) determines that the braking force applying means (217) is at a position along the braking force application axis (Xb) between the maintenance position and the rest position; b) The safety unit determines that the braking force applying means (217) is moving from the rest position to the maintenance position based on the change over time of the electrical position signal (221). The electromechanical brake actuator (400) according to Claim 9.

11. The safety unit (401) is also configured to receive a maintenance verification signal (223) configured to take a first value indicating non-confirmation of permission to set the braking force applying means (217) to the maintenance position and a second value indicating confirmation of permission to set the braking force applying means (217) to the maintenance position. The safety unit (401) is configured as follows: - Prevent the power signal (405) from reaching the electromechanical module (201) via the first cutoff means (403'); a) Both the maintenance request signal (222) and the maintenance verification signal (223) take their respective first values, and the safety unit (401) determines, based on the value of the electrical position signal (221), that the braking force applying means (217) is at a position along the braking force application axis (Xb) between the maintenance position and the rest position; b) Based on the change over time of the value of the electrical position signal (221), the safety unit determines that the braking force applying means (217) is moving from the rest position to the maintenance position; and / or the safety unit (401) is configured as follows: - Prevent the power signal (405) from reaching the electromechanical module (201) via the first cutoff means (403') when: a) The maintenance request signal (222) takes its first value and the maintenance verification signal (223) does not take its first value, or the maintenance request signal (222) takes its second value and the maintenance verification signal (223) does not take its second value; b) The safety unit (401) determines, based on the value of the electrical position signal (221), that the braking force applying means (217) is at a position along the braking force application axis (Xb) between the maintenance position and the rest position; and / or the safety unit (401) is further configured as follows: - Allow the power signal (405) to reach the electromechanical module (201) via the first cutoff means (403') when both the maintenance request signal (222) and the maintenance verification signal (223) take their respective second values and the safety unit (401) determines, based on the value of the electrical position signal (221), that the braking force applying means (217) is at the rest position; The electromechanical brake actuator (400) according to claim 10.

12. The safety unit (401) is also configured as follows: - When the safety unit prevents the power signal (405) from reaching the electromechanical module (201) via the first shut-off means (403'), it prevents the brake force control signal (204) issued by the service brake control unit (202) from reaching the electromechanical module (201) via the second shut-off means (406). The electromechanical brake actuator (400) according to any one of claims 9 to 11.

13. The safety unit (401) is configured as follows: - Via the first shut-off means (403'), both the maintenance request signal (222) and the maintenance verification signal (223) take their respective second values, and when the safety unit (401) determines based on the value of the electrical position signal (221) that the brake force applying means (217) is in the maintenance position, it prevents the power signal (405) from reaching the electromechanical module (201). The electromechanical brake actuator (400) according to claim 11.

14. Comprising force sensor means (212) configured to generate a brake force indicating electrical signal (213) which is a value indicating the value of the brake force generated by the electromechanical module (201). The service brake control unit (202) is configured to receive the brake force indicating electrical signal (213). The electromechanical brake actuator (400) according to any one of claims 9 to 13.

15. A brake system including a plurality of the electromechanical brake actuators (400) according to claim 2 or claim 10, wherein the brake system comprises a control unit (500) configured to be connected to the plurality of electromechanical brake actuators (400) via communication means (501). The control unit (500) is configured to receive the following: - A parking brake signal (502) whose value indicates whether the parking brake is applied. - At least one speed signal (503) indicating the speed of the railway vehicle or train. - A maintenance signal (504) indicating a request to perform a maintenance cycle on the brake system. The control unit (500) is configured as follows: - When the maintenance signal (504) takes a value indicating a maintenance requirement, and the parking brake signal (502) takes a value indicating that the parking brake is applied, and the speed signal (503) takes a value indicating a vehicle speed of zero, generate the maintenance requirement signal (222) having its second value to be transmitted to at least one of the plurality of electromechanical brake actuators (400) via the communication means (501). - When at least one of the following occurs: the maintenance signal (504) takes a value not indicating a maintenance requirement, the parking brake signal (502) takes a value indicating that the parking brake is not applied, and the speed signal (503) takes a value indicating a non-zero vehicle speed, generate the maintenance requirement signal (222) having its first value to be transmitted to the plurality of electromechanical brake actuators (400) via the communication means (501). A brake system characterized by the above.

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