Brake unit for rail vehicle

Abstract

A rail vehicle brake unit (200) includes a brake actuator (120), at least one pressing member (211), a gear assembly (220), an electric motor (230), and a backup power unit (123). The brake actuator (120) receives a brake command (cmdB) and generates an electric braking force signal (BF) to the electric motor (230) which in turn acts on the gear assembly (220) to bring the at least one pressing member (211) to a specified position relative to a rotatable member (110) mechanically coupled to at least one wheel (105) of the rail vehicle in order to apply a braking force thereto. During operation of the rail vehicle, the backup power unit (123) receives power (W) from a power line (140) in the rail vehicle and accumulates the received power (W). The backup power unit (123) supplies accumulated power to a control circuit in the brake actuator (120) and the electric motor (230) in the event of a power failure (PF) of the power (W) received in the brake actuator (120).

Description

Technical Field

[0001] The present invention generally relates to the deceleration of rail vehicles. In particular, the present invention relates to a brake unit for a rail vehicle according to the preamble of claim 1. Background Art

[0002] When an electric rail vehicle is in operation, the onboard electric motor is usually used as a generator for decelerating the rail vehicle. However, for efficiency and safety reasons, this braking strategy cannot be relied upon alone. In particular, it is always necessary to ensure emergency braking functionality and a braking function that ensures that the rail vehicle remains stationary after it has stopped.

[0003] In many cases, the same brake unit is used for different types of brake functionality, such as service brake, emergency brake and parking brake. Today's rail vehicle brakes typically use pneumatically adjusted brakes. This is particularly disadvantageous because they are slow and imprecise to adjust, but also because there is a risk of leakage and the resulting malfunction.

[0004] Recently, electronically controlled brakes have been proposed as an alternative to pneumatically regulated brakes. For example, US 2020 / 0198605 describes a microcomputer-controlled electromechanical braking system comprising an electromechanical brake control device and an electromechanical brake unit. The electromechanical brake control device includes a brake microcomputer control unit, an electromechanical control unit, and a backup power supply module. The brake microcomputer control unit receives a brake command signal sent by the driver or the automatic driving system, performs calculations for the target braking force and brake management. When the electromagnetic brake is de-energized, the screw and nut are arranged to lock the brake to maintain the braking force. When the torque motor rotor rotates in the opposite direction, the nut moves in the opposite direction in translation, and the braking force is released.

[0005] US2016 / 0193928 shows a backup power system for a railway power unit, the backup power system including an emergency backup generator that enables traction motors and accessories on the power unit to continue to operate when the main generator and / or auxiliary power unit (APU) become inoperable. The backup generator can provide power to accessories on the railcar when the APU becomes inoperable and when power provided by the APU is diverted to the traction motors because the main generator has become inoperable.

[0006] Thus, an electromechanical brake system is known which has a locking mechanism to maintain the applied braking force when the power supply to the brake fails. There is also a solution for providing backup power to accessories on a railcar when the main generator becomes inoperable. However, there is a lack of a technical solution to ensure that the electrically controlled brake unit remains operable when the power supply to the brake unit is interrupted. Summary of the invention

[0007] It is therefore an object of the present invention to solve the above-mentioned problems and to provide an improved reliability of an electrically operated brake unit for a rail vehicle.

[0008] According to the present invention, the purpose is achieved by a brake unit for a rail vehicle, the brake unit comprising a brake actuator, at least one pressing member, a gear assembly, a motor and a backup power unit. The brake actuator is configured to receive a brake command and generate an electric brake force signal in response to the brake command. The at least one pressing member is configured to apply a brake force to a rotatable member that is mechanically connected to at least one wheel of the rail vehicle. The gear assembly is arranged to mechanically operate the at least one pressing member. The motor is configured to act on the gear assembly in response to the electric brake force signal so that the at least one pressing member moves toward or away from the rotatable member and reaches a specified position relative to the rotatable member. The backup power unit is configured to receive power from a power line in the rail vehicle during operation of the rail vehicle and accumulate the received power. In the event of a power failure in the power received via the power line in the brake actuator, the backup power unit is configured to provide the accumulated power to the control circuit in the brake actuator and the motor.

[0009] The above brake unit is advantageous because it can still function as a service brake even if the power supply cable for the brake unit is broken. At least in theory, the brake unit can also continue to operate as a service brake in the event of such a power failure if the signal line for transmitting the brake command is still intact.

[0010] According to one embodiment of the invention, the backup power unit comprises at least one rechargeable battery and a battery charger connected to the power line. The battery charger is configured to transfer power received from the power line to the at least one rechargeable battery. If reception of power in the brake actuator is interrupted, the at least one rechargeable battery is arranged to feed power to control circuits in the brake actuator and the electric motor.

[0011] Furthermore, it is advantageous to arrange the control circuit in the brake actuator, since thereby the brake unit can be controlled in a highly distributed manner, which minimizes the sensitivity of the brake control to electromagnetic interference.

[0012] Alternatively or additionally, according to one embodiment of the invention, the backup power unit comprises at least one capacitive element, for example in the form of one or more relatively powerful capacitors. The backup power unit also comprises at least one rectifier, for example a diode, connected to the power line and configured to transfer power received from the power line to the at least one capacitive element. Similar to the above, if power reception in the brake actuator is interrupted, the at least one capacitive element is arranged to feed power to the control circuit in the brake actuator and the motor. Thus, a space-saving power supply for emergency situations is provided.

[0013] Preferably, the brake actuator includes a backup power unit, so that even if a cable break occurs immediately outside the brake actuator, power supply can be ensured.

[0014] According to another embodiment of the invention, a processing unit is included in the control circuit of the brake actuator. The processing unit is in turn configured to generate an electric brake force signal based on the brake command. It is beneficial to include a processing unit in the brake actuator because it allows high flexibility in the way the electric brake force signal is generated and / or the basis for generating said signal.

[0015] According to yet another embodiment of the invention, if the processing unit detects that there is a power failure in the power received via the power line in the brake actuator, the processing unit is configured to generate an electric braking force signal in such a way that the electric motor acts on the gear assembly so that the at least one pressing member applies a predefined emergency braking force to the rotatable member. Typically, if the power line fails, this also means that the communication with the brake unit is interrupted or destroyed. Therefore, it is a reasonable strategy to activate emergency braking in response to an input power failure in the brake unit.

[0016] According to a further embodiment of the invention, the brake actuator comprises an accelerometer, which is configured to generate at least one vector signal, which vector signal is representative of the acceleration in at least one dimension of the rail car in which the brake actuator is comprised. Thus, the at least one vector signal is representative of the movement of the rail car. The brake actuator is hereby configured to generate the electric braking force signal further based on the at least one vector signal. Thus, the brake actuator can dynamically generate the electric braking force signal depending on how the rail car reacts to the applied braking force. This in turn allows for efficient braking.

[0017] According to another embodiment of the present invention, the brake unit includes a position sensor configured to generate a position signal indicating the angular position of the power transmission shaft of the motor. Here, the brake actuator is configured to receive the position signal and determine whether the specified position of the at least one pressing member relative to the rotatable member has been reached based on the position signal. If so, the brake actuator is configured to stop generating the electric braking force signal. Therefore, braking can be effectively and reliably achieved.

[0018] According to another embodiment of the invention, the brake unit comprises a force sensor configured to generate a sensor signal representing the magnitude of the force applied by the at least one pressing member on the rotatable member. The brake actuator is here configured to receive the sensor signal and to generate a status message based on the sensor signal, the status message confirming that the brake command has taken effect. This is advantageous because it can present sufficient feedback information to the driver of the rail vehicle.

[0019] Alternatively, the processing unit may be configured to determine the magnitude of the force exerted by the at least one pressing member on the rotatable member based on the drive current fed to the motor. Based on the force, the processing unit is in turn configured to generate a status message confirming that the braking command has taken effect. Thus, no dedicated force sensor is required.

[0020] According to another embodiment of the invention, the brake actuator has a wireless interface configured to receive a wireless signal representing the rotational speed of the at least one wheel mechanically coupled to the rotatable member. Here, the brake actuator is configured to dynamically generate the electric brake force signal further based on the rotational speed of the at least one wheel. Thus, the brake actuator can dynamically generate the electric brake force signal depending on how the braking affects the wheel speed, so that, for example, wheel locking can be avoided even during emergency braking due to a power failure.

[0021] According to a further embodiment of the invention, the gear assembly comprises a worm gear arrangement, the gear ratio of which substantially prevents the specified position of the at least one pressing member relative to the rotatable member from being changed due to a movement of the member. This means that any unintentional repositioning of the at least one pressing member can be avoided.

[0022] According to another embodiment of the present invention, the brake actuator is connected to at least one data bus in the rail vehicle, such as a serial bus. The at least one data bus is configured to transmit control signals and / or status messages to the brake actuator, or to transmit control signals and / or status messages from the brake actuator. Thus, the brake unit can be controlled in an efficient and flexible manner and in a highly reliable manner. Preferably, the brake actuator is also configured to receive a brake command as a control signal via one of the data buses.

[0023] Further advantages, advantageous features and applications of the invention will become apparent from the following description and the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will now be explained in more detail by means of preferred embodiments disclosed as examples and with reference to the accompanying drawings.

[0025] Figure 1 Schematically shows a rail vehicle equipped with a brake unit according to one embodiment of the present invention;

[0026] Figure 2 A brake unit according to an embodiment of the present invention is shown;

[0027] Figure 3 and Figure 4 shows a backup power unit according to various embodiments of the present invention; and

[0028] Figure 5 An accelerometer for recording the movement of a rail vehicle according to one embodiment of the present invention is shown; and

[0029] Figure 6 A mechanical self-locking mechanism according to an embodiment of the present invention is described. DETAILED DESCRIPTION

[0030] Figure 1 A rail vehicle 100 is schematically shown which is equipped with a brake unit 200 according to an embodiment of the present invention. Figure 2 FIG. 4 is a perspective view of a brake unit 200 according to an embodiment of the present invention.

[0031] The proposed brake unit 200 includes a brake actuator 120 , at least one pressing member (illustrated here by 211 and 212 ), a gear assembly 220 , an electric motor 230 , and a backup power unit 123 .

[0032] The brake actuator 120 is configured to receive a brake command cmd, for example via a data bus 150 in the rail vehicle 100 configured to transmit a control signal CS. BThe data bus may be a serial bus in CAN (Controller Area Network) format. Alternatively, the data bus 150 may use the Factory Instrumentation Protocol (FIP), the latest definition of which can be found in European standard EN50170; for example the Multifunction Vehicle Bus (MVB) protocol defined by European standard EN61375 or TCP / IP (Transmission Control Protocol / Internet Protocol). In response to the braking command cmd B , the brake actuator 120 is configured to generate an electric braking force signal BF.

[0033] Each of the pressing members 211 and 212 is configured to apply a braking force to a rotatable member 110 that is mechanically coupled to at least one wheel 105 of the rail vehicle 100. Therefore, the pressing members 211 and 212 may be illustrated as a pair of calipers, and the rotatable member 110 may be illustrated as a brake disc. Alternatively, the rotatable member 110 may be illustrated as a brake drum that is mechanically coupled to at least one wheel 105 of the rail vehicle 100. In this case, it is sufficient to utilize a single pressing member that is configured to press against the outer surface or inner surface of the brake drum.

[0034] The gear assembly 220 is arranged to mechanically operate the pressing members 211 and 212. In terms of function, the gear assembly 220 is positioned between the motor 230 and the pressing members 211 and 212. Figure 6 An example of a gear assembly 220 according to one embodiment of the present invention is shown, wherein the gear assembly 220 includes a worm gear arrangement 300. In response to the electric braking force signal BF, the motor 230 is configured to act on the gear assembly 220 so that the pressing members 211 and 212 move toward or away from the rotatable member 110 and reach a specified position relative to the rotatable member 110. Here, the first specified position may correspond to a released state of the brake, i.e., wherein the rotatable member 110 and the at least one wheel 105 can rotate; and the second specified position may correspond to a fully braked state, wherein the pressing members 211 and 212 apply a braking force to the rotatable member 110 so as to keep the at least one wheel 105 immobile. Of course, according to the present invention, any number of intermediate states between the first state and the second state can be envisaged, which correspond to various magnitudes of braking force applied to the at least one wheel 105. Therefore, the electric braking force signal BF can, for example, command an adjustment or release of the braking force that has been applied.

[0035] The backup power unit 123 is configured to receive power W from the power line 140 in the rail vehicle 100 during operation of the rail vehicle 100. The power W may be received in the rail vehicle 100 via a collector, or the power W may originate from a generator on the rail vehicle 100. The backup power unit 123 is configured to accumulate the received power W; and in the event of a power failure PF in the brake actuator 120 receiving the power W via the power line 140, the backup power unit 123 is configured to provide the accumulated power to the control circuits in the brake actuator 120 and the motor 230.

[0036] Figure 3 A backup power unit 123 according to a first embodiment of the invention is shown, wherein the backup power unit 123 comprises at least one rechargeable battery 333. Here, the backup power unit 123 further comprises a battery charger 331, which is connected to the power line 140 and is configured to transfer power W received from the power line 140 to the at least one rechargeable battery 333. The at least one rechargeable battery 333 is arranged to feed power to the control circuits in the brake actuator 120 and the electric motor 230 in the event of an interruption in the reception of power W in the brake actuator 120.

[0037] Figure 4 The backup power unit 123 according to the second embodiment of the present invention is shown, wherein the backup power unit 123 comprises at least one capacitive element 433, such as one or more capacitors, which preferably have a relatively high capacitance. The backup power unit 123 also comprises at least one rectifying element 431. Figure 4 , this is represented by diode 431. If power line 140 is configured to transmit power W in the form of direct current, such a single diode is generally sufficient to prevent accidental discharge of charge from at least one capacitive element 433 in the event of, for example, a cable breakage external to backup power unit 123.

[0038] If the power W received from the power line 140 is of the alternating current type, it is typically advantageous for the backup power unit 123 to include a rectifying element in the form of a diode bridge comprising four diodes connected to the power line 140 and configured to convert the incoming alternating current into direct current for supply to the at least one capacitive element 433.

[0039] In any case, regardless of the type of power W received from the power line 140, similar to the above, if power reception in the brake actuator 120 is interrupted, the at least one rechargeable battery 433 is arranged to feed power to the control circuits in the brake actuator 120 and the motor 230.

[0040] For reasons of safety and reliability, it is generally preferred to include a backup power unit 123 in the brake actuator 120. That is, in this case, the brake actuator 120 can continue to be operable even if all wiring of the brake actuator 120 is torn off, for example, to achieve emergency braking.

[0041] According to one embodiment of the present invention, the control circuit in the brake actuator 120 comprises a processing unit 125, which is configured to: B The processing unit 125 may also be configured to supervise the power W received in the brake actuator 120 via the power line 140. According to one embodiment of the present invention, if the processing unit 125 detects that there is a power failure PF in the power W received in the brake actuator 120 via the power line 140, the processing unit 125 is configured to induce emergency braking by generating the electric braking force signal BF, so that the motor 230 acts on the gear assembly 220, so that the pressing members 211 and 212 apply a predefined emergency braking force to the rotatable member 110.

[0042] The motor 230 may be implemented as a stepper motor. This is advantageous because a stepper motor can provide high precision positioning of its power transmission shaft without the need for a position sensor for feedback. A stepper motor is typically a brushless DC motor that divides a full rotation into a plurality (e.g., 100) of equal steps, which may be provided by a gear-shaped iron rotor with 25 teeth, with each step rotating at an angle of 3.6 degrees. A stepper motor may be commanded by open loop control to move and maintain a position at one of these steps, provided that the motor is suitable for the application in terms of torque and speed.

[0043] Alternatively, according to one embodiment of the present invention, the brake unit 200 includes a dedicated position sensor 235, which is configured to generate a position signal P, which indicates the angular position of the power transmission shaft of the motor 230. Here, the brake actuator 120 is configured to receive the position signal P, and determine whether the pressing members 211 and 212 have reached the specified position relative to the rotatable member 110 based on the position signal. If the brake actuator 120 determines that the pressing members 211 and 212 have reached the specified position relative to the rotatable member 110, the brake actuator 120 is configured to stop generating the electric braking force signal BF. Therefore, the pressing members 211 and 212 remain stationary in the specified position. However, if the brake unit 200 determines that the mutually associated specified position has not been reached, the brake unit 200 is configured to continue to generate the electric braking force signal BF until the mutually associated specified position has been reached.

[0044] According to one embodiment of the present invention, the brake actuator 120 includes an accelerometer 127 configured to generate at least one vector signal VS representing an acceleration a in at least one dimension of the rail car containing the brake actuator 120. X 、a Y 、a Z 、a R 、a P and / or a W . Thus, the at least one vector signal VS represents the movement of the rail vehicle, for example in the form of a speed along the track. Furthermore, the brake actuator 120 is configured to generate the electric brake force signal BF further based on the at least one vector signal VS. Thus, the electric brake force signal BF can be dynamically adjusted in response to how the rail vehicle reacts to the electric brake force signal BF during the braking process.

[0045] According to one embodiment of the invention, the brake unit 200 comprises a force sensor 250 configured to generate a sensor signal F, which is representative of the magnitude of the force exerted by the pressing members 211 and 212 on the rotatable member 110. The control circuit in the brake actuator 120 is configured to receive the sensor signal F and, based on the signal, generate a status message SS confirming the braking command cmd B As a result, appropriate feedback information can be presented to the driver of the rail vehicle, for example on a control panel in the driver's cab.

[0046] According to another embodiment of the invention, the processing unit 125 is configured to determine the magnitude of the force exerted by the at least one pressing member 211 and 212 on the rotatable member 110 based on the drive current fed to the motor 230. In other words, the functionality of the above-mentioned force sensor 250 is implemented here inside the processing unit 125, for example by running software that uses the drive current as an input parameter to calculate the sensor signal F. The processing unit 125 is also configured to generate a status message SS, which confirms the braking command cmd B Based on the derived force already in effect, typically when a predefined force has been determined.

[0047] According to one embodiment of the present invention, the brake actuator 120 includes a wireless interface 129 configured to receive a wireless signal representing the rotation speed of at least one wheel 105 mechanically coupled to the rotatable member 110. Here, the brake actuator 120 is configured to generate the electric braking force signal BF further based on the rotation speed of the at least one wheel 105. As a result, the brake actuator 120 can dynamically generate the electric braking force signal BF depending on how the braking affects the wheel speed, so that, for example, wheel locking can be avoided. Since the rotation speed signal is received wirelessly, such control of the electric braking force signal BF can be performed even in the case of emergency braking caused by a power failure.

[0048] According to one embodiment of the present invention, the brake unit 200 further includes a force sensor 250 configured to generate a sensor signal F, which represents the magnitude of the force applied by the pressing members 211 and 212 on the rotatable member 110. The force sensor 250 can be a ring torsion type sensor arranged on the first axis A1 included in the mechanical connection between the gear assembly 220 and the first pressing member 211 in the pressing member. Additionally or alternatively, the force sensor 250 can be arranged on the second axis A2 included in the mechanical connection between the gear assembly 220 and the second pressing member 212 in the pressing member.

[0049] Additionally or alternatively, one or more load cells, for example load cells of the bending, shear, compression and / or tension type, may be arranged on the first pressing member 211 and the second pressing member 212 .

[0050] It is generally advantageous to include the processing circuitry in the brake actuator 120 and to generate the sensor signal F, the at least one vector signal VS and / or the position signal P physically close to the brake actuator 120. That is, this reduces the risk of the signals being degraded before being processed, for example due to interference from radiated electromagnetic energy or by other means.

[0051] Preferably, the brake actuator (120) is configured to receive a sensor signal (F) and to generate a status message (SS) based on the sensor signal, the status message confirming the brake command (cmd B ) has come into effect.

[0052] Brake command cmd BIt can be sent as a control signal CS via a data bus 150 in the rail vehicle 100. According to one embodiment of the present invention, the rail vehicle 100 comprises at least one first data bus 150, which is configured to transmit the control signal CS. Preferably, the rail vehicle 100 preferably further comprises at least one second data bus 160, which is configured to transmit, for example, a status message SS reflecting the current state of the brake and / or the relative positions between the first pressing member 211 and the second pressing member 212. Similar to the data bus 150, the at least one second data bus 160 is preferably a serial bus using one of the above-mentioned communication formats.

[0053] Reference now Figure 6 , we see an example of a gear assembly 220 according to an embodiment of the present invention, wherein the gear assembly 220 includes a worm gear arrangement 600 having a gear ratio that is configured to substantially prevent the respective designated positions between the pressing members 211 and 212 and the rotatable member 110 from being changed by movement of one or both of the pressing members 211 and / or 212, i.e., pushing / pulling the load pad 650 to rotate the power transmission shaft 610 in the forward direction RF or the rearward direction RB. Therefore, the designated positions of the pressing members 211 and 212 relative to the rotatable member 110 cannot be changed by movement of the pressing members 211 and 212 by means other than via the worm gear arrangement 600. In other words, here, the worm gear arrangement 600 constitutes a self-locking mechanism for the pressing members 211 and 212.

[0054] Mechanical power is fed into the worm gear arrangement 600 via the power transmission shaft 610 of the motor 230. The motor 230 is configured to rotate the power transmission shaft 610 in the forward direction RF or the rearward direction RB. Thus, the load pad 650 is fed outwardly or inwardly, for example, between a first position P1 and a second position P2, respectively, by the action of the input worm 620 on the worm gear 630 acting on the lifting screw 640. Preferably, the worm gear arrangement 600 further comprises a first protective tube 615 and a second protective tube 645 covering the input worm 620 and the lifting screw 640, respectively.

[0055] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0056] When used in this specification, the terms "comprises / comprising" are used to specify the presence of stated features, integers, steps or components. The terms do not exclude the presence or addition of one or more additional elements, features, integers, steps or components or groups thereof. The indefinite article "a" or "an" does not exclude a plurality. In the claims, the word "or" should not be interpreted as an exclusive or (sometimes referred to as "XOR"). On the contrary, unless otherwise indicated, expressions such as "A or B" cover all cases of "A and not B", "B and not A" and "A and B". The mere fact that certain measures are cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope.

[0057] It should also be noted that features from the various embodiments described herein may be combined freely, unless it is explicitly stated that such a combination is inappropriate.

[0058] The invention is not limited to the embodiments described in the figures but may be varied freely within the scope of the claims.

Claims

1. A brake unit (200) for a rail vehicle (100), the brake unit (200) comprising: A brake actuator (120) configured to receive a brake command (cmd B ), and generating an electric braking force signal (BF) in response to the braking command, at least one pressing member (211, 212) configured to apply a braking force to a rotatable member (110) mechanically coupled to at least one wheel (105) of the rail vehicle (100), a gear assembly (220) arranged to mechanically operate the at least one pressing member (211; 212), an electric motor (230) configured to act on the gear assembly (220) in response to the electric braking force signal (BF) so as to move the at least one pressing member (211; 212) toward or away from the rotatable member (110) and reach a specified position relative to the rotatable member, and A backup power unit (123) is configured to receive power (W) from a power line (140) in the rail vehicle (100) during operation of the rail vehicle (100); to accumulate the received power (W); and in the event of a power failure (PF) in the power (W) received via the power line (140) in the brake actuator (120), to provide the accumulated power to the control circuits in the brake actuator (120) and the motor (230).

2. The brake unit (200) according to claim 1, wherein the backup power unit (123) comprises: at least one rechargeable battery (333), and A battery charger (331) connected to the power line (140) and configured to transfer power (W) received from the power line (140) to the at least one rechargeable battery (333), wherein the at least one rechargeable battery (333) is arranged to feed power to the brake actuator (120) and the control circuit in the electric motor (230) in the event that reception of the power (W) in the brake actuator (120) is interrupted.

3. The brake unit (200) according to claim 1 or 2, wherein the backup power unit (123) comprises: at least one capacitive element (433), and at least one rectifying element (431), the at least one rectifying element being connected to the power line (140) and being configured to transfer the power (W) received from the power line (140) to the at least one capacitive element (433), The at least one capacitive element (433) is arranged to feed power to the control circuits in the brake actuator (120) and the electric motor (230) when the power (W) received in the brake actuator (120) is interrupted.

4. The brake unit (200) according to any of the preceding claims, wherein the backup power unit (123) is comprised in the brake actuator (120).

5. The brake unit (200) according to any one of the preceding claims, wherein the control circuit included in the brake actuator (120) comprises a processing unit (125) configured to process the brake command (cmd B ) to generate the electric braking force signal (BF).

6. The brake unit (200) according to claim 5, wherein if the processing unit (125) detects the presence of a power failure (PF) in the power (W) received in the brake actuator (120) via the power line (140), the processing unit (125) is configured to: The electric braking force signal (BF) is generated so that the electric motor (230) acts on the gear assembly (220) to cause the at least one pressing member (211; 212) to apply a predefined emergency braking force to the rotatable member (110).

7. The brake unit (200) according to any of the preceding claims, wherein the brake actuator (120) comprises an accelerometer (127) configured to generate at least one vector signal (VS) representing an acceleration (a) in at least one dimension of a rail car in which the brake actuator (120) is located. X 、a Y 、a Z 、a R 、a P、 a W ), the at least one vector signal (VS) representing the movement of the rail car, and the brake actuator (120) is configured to generate the electric braking force signal (BF) further based on the at least one vector signal (VS).

8. The brake unit (200) according to any one of the preceding claims, further comprising a position sensor (235) configured to generate a position signal (P) indicating an angular position of a power transmission shaft of the electric motor (230), and The brake actuator (120) is configured to receive the position signal (P) and determine whether the at least one pressing member (211, 212) has reached the specified position relative to the rotatable member (110) based on the position signal; and if so, stop generating the electric braking force signal (BF).

9. The brake unit (200) according to any one of the preceding claims, further comprising a force sensor (250) configured to generate a sensor signal (F) representing the magnitude of the force exerted by the at least one pressing member (211, 212) on the rotatable member (110), and The brake actuator (120) is configured to receive the sensor signal (F) and to generate a status message (SS) based on the sensor signal, the status message confirming the brake command (cmd B ) has come into effect.

10. The brake unit (200) according to claim 5 or 6, wherein the processing unit (125) is configured to: determining the magnitude of the force exerted by the at least one pressing member (211, 212) on the rotatable member (110) based on the drive current fed to the motor (230), and A status message (SS) is generated based on the force, the status message confirming the braking command (cmd B ) has come into effect.

11. The brake unit (200) according to any one of the preceding claims, wherein: The brake actuator (120) further comprises a wireless interface (129) configured to receive a wireless signal indicative of a rotational speed of the at least one wheel (105) mechanically coupled to the rotatable member (110), and The brake actuator (120) is configured to generate the electric brake force signal (BF) further based on the rotational speed of the at least one wheel (105).

12. A brake unit (200) according to any of the preceding claims, wherein the gear assembly (220) comprises a worm gear arrangement (600), the gear ratio of which is configured to substantially prevent the specified position between the at least one pressing member (211, 212) and the rotatable member (110) from being changed due to movement of the at least one pressing member (211, 212).

13. A braking unit (200) according to any of the preceding claims, wherein the brake actuator (120) is connected to at least one data bus (150, 160) in the rail vehicle (100), and the at least one data bus is configured to transmit at least one of a control signal (CS) and a status message (SS).

14. The brake unit (200) according to claim 13, wherein the brake actuator (120) is configured to receive the brake command (cmd) via one of the at least one data buses (150). B ) as one control signal (CS) among the at least one control signal.

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