Braking device for a vehicle and method for operating a braking device

Abstract

The present invention provides a braking device (10) for an electric vehicle (F), comprising at least a first braking device (BE1) which can be attached to at least one wheel (R1, R2) of a front axle (VA) of the electric vehicle (F) and which can exert a braking effect on this wheel; and at least a first central braking device (BZ1) which can be attached to the front axle (VA) and with which a central braking effect can be exerted on the front axle and thereby on the wheels of the front axle, wherein the first central braking device (BZ1) can be operated by and connected to a power supply for an electric drive of the electric vehicle (F).

Description

[0001] The present invention relates to a braking device for a vehicle and a method for operating a braking device. State of the art

[0002] Conventional electric vehicles can be equipped with the same hydraulically actuated friction brakes as vehicles with combustion engines. Alternative concepts can be used for decentralized brake actuation, particularly electromechanical brakes (EMB), although these have not yet been widely adopted in series production.

[0003] On the front axle, redundant actuators with redundant control and redundant power supply may typically be required in order to achieve a certain vehicle deceleration even in the event of single electrical faults.

[0004] In addition to the friction brakes, the generator can be used for deceleration in electric vehicles.

[0005] In eddy current brakes, a rotor with good magnetic and electrical conductivity can usually be rotated in an inhomogeneous magnetic field, whereby it can experience a certain number of changes in the intensity and direction of the magnetic field or magnetic flux during one revolution.

[0006] Such a movement can induce a current in the rotor, resulting from the law of induction or the Lorentz force. The generated currents can form a circular pattern in the rotor, provided the magnetic field is not uniformly strong across the entire rotor surface. Consequently, the circular currents can generate a magnetic field, which, in interaction with the excitation magnetic field, can decelerate the rotor. Eddy-current brakes can usually be designed to be frictionless.

[0007] A combination of eddy current brake and friction brake can also be provided

[0008] DE 10 2020 206 349 A1 describes a braking device for an electric drive axle. Disclosure of the invention

[0009] The present invention provides a braking device for a vehicle according to claim 1 and a method for operating a braking device according to claim 10.

[0010] Preferred further training is the subject of the subclaims. Advantages of the invention

[0011] The idea underlying the present invention is to provide a braking device for a vehicle and a method for operating a braking device, wherein a central brake on an axle is available as a redundant braking element.

[0012] According to the invention, the braking device for an electric vehicle comprises at least one first braking device, which can be attached to at least one wheel of a front axle of the electric vehicle and can act on this wheel with a braking effect; at least one first central braking device, which can be attached to the front axle and with which a central braking effect can be acted on the front axle and thereby on the wheels of the front axle, wherein the first central braking device can be operated by a power supply for an electric drive of the electric vehicle and can be connected to this.

[0013] Redundancy can advantageously be achieved for existing brake actuators and their control for electric vehicles with electromechanical brakes, particularly by using a central redundant brake element that can act on both wheels of an axle. Furthermore, the costs incurred for such a braking system can be reduced.

[0014] According to the invention, a braking element (e.g., an eddy-current brake) integrated centrally into the vehicle's drive train can advantageously be used as a redundant actuator for electromechanical wheel brakes. Such integration can be achieved in such a way that at least one such central braking element can act on one of the vehicle's axles and thus on the rotation of the wheels of that axle. In this way, only one redundant actuator may be necessary for the entire axle because a braking torque generated by this central actuator (braking device) can be evenly distributed to both wheels by the drive train with its differential gear, thus reducing or preventing unwanted yaw of the vehicle.

[0015] Furthermore, the invention enables the use of electromechanical brakes without redundancy on the front axle. It also allows the use of inexpensive drum brakes on the front axle (they are thermally relieved by eddy current brakes). Furthermore, the economical use of electromechanical brakes for heavy vehicles with very high braking force requirements on the front axle is also possible.

[0016] Since the structure of the invention can create redundancy in the braking devices, this can result in reduced effort and lower costs for the redundancy on the existing (EMB) wheel brakes.

[0017] Furthermore, wear-free or at least wear-reduced support of existing (EMB) brakes during normal operation can be enabled. The design of the invention allows a reduction in the load spectrum for (EMB) brakes (first and / or second braking devices) through the central braking device (e.g., an eddy-current brake), even when the generator is not braking, for example, due to the battery at low temperatures.

[0018] Downsizing the (EMB) braking devices (first / second) may be possible. In load cases for the (EMB) brakes, for example, during fading or dynamic interventions on individual wheels (e.g., through ESP control), part of the braking torque can be generated by the central braking device (e.g., an eddy-current brake). During dynamic interventions, for example, on the outside of the front corner, slight co-braking of the inside front wheel can be tolerated.

[0019] Furthermore, brake dust can be reduced by reducing the use of the friction brake.

[0020] Better control dynamics can also be achieved by superimposing several actuators on one axle and, if necessary, by high dynamics of the central brake actuator (e.g. with an eddy current brake as the central braking device).

[0021] Central braking means that it acts centrally on the axle, meaning that all wheels of the corresponding axle can be braked.

[0022] According to a preferred embodiment of the braking device, it comprises at least one second braking device which can be attached to at least one further wheel of a rear axle of the electric vehicle and can act on this wheel with a braking effect.

[0023] According to a preferred embodiment of the braking device, it comprises at least a second central braking device which can be attached to the rear axle and with which a central braking effect can be exerted on the rear axle and thus on the wheels of the rear axle.

[0024] According to a preferred embodiment of the braking device, the first central braking device comprises an eddy current brake with which an eddy current braking effect can be exerted on the front axle.

[0025] According to a preferred embodiment of the braking device, the second central braking device comprises an eddy current brake with which an eddy current braking effect can be exerted on the rear axle, wherein the second central braking device can be operated by the power supply for the electric drive of the electric vehicle or by an on-board electrical system of the electric vehicle and can be connected thereto.

[0026] According to a preferred embodiment of the braking device, the first central braking device can be coupled to a transmission of the electric vehicle.

[0027] According to a preferred embodiment of the braking device, the second central braking device can be coupled to a transmission of the electric vehicle.

[0028] According to a preferred embodiment of the braking device, the first braking device comprises an electromagnetically actuatable disc or drum brake or an electro-hydraulic brake.

[0029] According to a preferred embodiment of the braking device, the second braking device comprises an electromagnetically actuatable disc or drum brake or an electro-hydraulic brake.

[0030] According to the invention, the method for operating a braking device comprises providing a braking device according to the invention; and generating a redundant braking effect on the front axle by the first and optionally by the second central braking device.

[0031] The redundant braking effect is meant as an addition to the effect of the braking devices (first, second).

[0032] The braking device can also be characterized by the features and advantages mentioned in connection with the method and vice versa.

[0033] The existing braking devices (first / second) on the vehicle and / or on the wheels (e.g. the EMBs) can be designed in such a way that they can achieve a predetermined vehicle deceleration in normal operation and can take over certain driving dynamics functions with wheel-individual braking interventions (differential torque left / right).

[0034] Furthermore, however, support from the central braking device(s) can also be taken into account, for example to take into account or support any fading and / or driving dynamics interventions.

[0035] An eddy current brake can be designed in such a way that in the event of a failure of one of the braking devices for the wheels (EMBs) or a failure of the 12V electrical system alone, a predetermined deceleration (e.g. 6.44 m / s 2 ). This is particularly possible for vehicles whose center of gravity is located in the front half of the vehicle, allowing sufficient tire forces to be transferred to the front axle. Redundancy of the LV electrical system is not necessarily required in such cases.

[0036] During comfort braking, the central braking system can support the generator to maximize wear-free braking and reduce the load spectrum of the EMB (first / second braking systems). Even during ABS, one or both of the central braking systems can dynamically brake.

[0037] It may be possible that by coupling the central braking device(s) via the differential, only as much braking torque as the wheel with the smallest coefficient of adhesion can deliver can be transferred to an axle.

[0038] A thermal dimensioning of the central braking device(s) can be reduced in such a way that a single braking from a predetermined maximum speed v_max can be enabled if it is only used for braking in the event of a fault.

[0039] Furthermore, for vehicles with a center of gravity far back in the vehicle, a redundant LV on-board network may be required, so that in the event of a single fault only individual wheel actuators fail and, for example, one of the second braking devices on the rear axle can be used additionally to achieve the predetermined deceleration (e.g. 6.44 m / s 2 ) in the fallback level.

[0040] If a redundant LV on-board network is available (e.g. due to steer-by-wire steering), the demand on the central braking device (first or second) can be further reduced, since in the case of a single fault usually only individual wheel brakes fail and then less braking torque / power is required from the central (first or second) braking device to achieve the predetermined minimum deceleration.

[0041] In an all-wheel-drive vehicle, a redundant actuator can be mounted on each driven axle as a central (first / second) braking device, either to increase deceleration in the event of a failure or to reduce the demands on the wheel brakes of that axle. Instead of an eddy-current brake, other types of brakes can also be installed centrally in the driveline as integrated braking elements (friction brakes, braking resistors), which can be capable of providing a predetermined braking torque / power for the fallback level.

[0042] It may also be possible to actuate the wheel brakes electrohydraulically. Furthermore, the (first / second) central brake system can also be controlled from the 12V vehicle electrical system.

[0043] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings. Short description of the drawings

[0044] The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing.

[0045] They show: Fig. 1 is a schematic representation of a braking device according to an embodiment of the present invention; Fig. 2 a block diagram of method steps of the method for operating a braking device according to an embodiment of the present invention.

[0046] In the figures, the same reference symbols denote the same or functionally identical elements.

[0047] Fig. 1 shows a schematic representation of a braking device according to an embodiment of the present invention. The braking device 10 shown for an electric vehicle F comprises a first braking device BE1 on each wheel of the front axle VA, which can act on this wheel with a braking effect; a first central braking device BZ1, which can be attached to the front axle VA (centrally in the vehicle, approximately centrally in the axle or deviating therefrom) and with which a central braking effect can be acted on the front axle and thus on the wheels of the front axle, wherein the first central braking device BZ1 can be operated by a power supply HV for an electric drive EM of the electric vehicle F and can be connected to this.

[0048] A second braking device BE2 can be present on each of the rear wheels R3, R4, which can be attached to at least one further wheel (R3, R4) of the rear axle HA of the electric vehicle F and can act on this wheel with a braking effect.

[0049] After Fig. 1, a rear axle HA is indicated, however, a second central braking device (BZ2) present there is not shown, but may be included, which can be attached to the rear axle HA and with which a central braking effect can be exerted on the rear axle and thus on the wheels of the rear axle.

[0050] The first central braking device BZ1 can comprise an eddy-current brake, with which an eddy-current braking effect can be exerted on the front axle. The second central braking device (BZ2) can comprise an eddy-current brake, with which an eddy-current braking effect can be exerted on the rear axle. The second central braking device (BZ2) can be operated by the power supply HV for the electric drive of the electric vehicle F or by an on-board electrical system LV of the electric vehicle (F) and can be connected to it.

[0051] After Fig. 1, vehicle F is equipped with an axle-centered eddy-current brake BZ1 as the first central braking device on the front axle VA, as well as four EMBs on the wheels R1, R2, R3, and R4. The eddy-current brake can be integrated into the drivetrain and connected to the transmission GT, allowing the gear ratio to be used to amplify the torque. Consequently, the central braking device BZ1 can be designed accordingly small. The EMBs as the first and second braking devices BE1 and BE2 on the wheels can be implemented, for example, as electromechanically actuated disc or drum brakes.

[0052] To control the central braking system BZ1, a high-voltage electrical system (HV) can be used as the power supply for the electric drive via the electric motor (EM). The EMBs can be supplied via a low-voltage (LV) electrical system (LV), e.g., with a voltage level of 12 V.

[0053] This design eliminates the need for additional redundancy in the on-board electrical system. Furthermore, the first central braking device BZ1 can be configured for a single, predetermined braking action.

[0054] The iECB stands for integrated Eddy Current Brake, in particular the eddy current brake module, which can be integrated into the drive train to provide the central braking torque for the axle.

[0055] Fig. 2 shows a block diagram of method steps of the method for operating a braking device according to an embodiment of the present invention.

[0056] In the method for operating a braking device, a braking device according to the invention is provided S1; and a redundant braking effect is generated S2 on the front axle by the first central braking device.

[0057] Although the present invention has been fully described above using the preferred embodiment, it is not limited thereto but can be modified in many ways. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 206 349 A1

[0008]

Claims

[1] Braking device (10) for an electric vehicle (F), comprising: - at least one first braking device (BE1) which can be attached to at least one wheel (R1, R2) of a front axle (VA) of the electric vehicle (F) and can act on this wheel with a braking effect; - at least one first central braking device (BZ1) which can be attached to the front axle (VA) and with which a central braking effect can be exerted on the front axle and thereby on the wheels of the front axle, wherein the first central braking device (BZ1) can be operated by a power supply for an electric drive of the electric vehicle (F) and can be connected thereto. [2] Braking device (10) according to claim 1, which comprises at least one second braking device (BE2) which can be attached to at least one further wheel (R3, R4) of a rear axle (HA) of the electric vehicle (F) and can act on this wheel with a braking effect. [3] Braking device (10) according to claim 1 or 2, which comprises at least one second central braking device (BZ2) which can be attached to the rear axle (HA) and with which a central braking effect can be exerted on the rear axle and thereby on the wheels of the rear axle. [4] Braking device (10) according to one of claims 1 to 3, wherein the first central braking device (BZ1) comprises an eddy current brake with which an eddy current braking effect can be exerted on the front axle. [5] Braking device (10) according to one of claims 3 to 4, as far as dependent on claim 3, in which the second central braking device (BZ2) comprises an eddy current brake with which an eddy current braking effect can be exerted on the rear axle, wherein the second central braking device (BZ2) can be operated by the power supply for the electric drive of the electric vehicle (F) or by an on-board electrical system of the electric vehicle (F) and can be connected to the latter. [6] Braking device (10) according to one of claims 1 to 5, wherein the first central braking device (BZ1) can be coupled to a transmission (GT) of the electric vehicle (F). [7] Braking device (10) according to one of claims 3 to 6, as far as dependent on claim 3, in which the second central braking device (BZ2) can be coupled to a transmission (GT) of the electric vehicle (F). [8] Braking device (10) according to one of claims 1 to 7, wherein the first braking device (BE1) comprises an electromagnetically actuatable disc or drum brake or an electro-hydraulic brake. [9] Braking device (10) according to one of claims 2 to 8, as far as dependent on claim 2, in which the second braking device (BE2) comprises an electromagnetically actuatable disc or drum brake or an electro-hydraulic brake. [10] Method for operating a braking device (10), comprising the steps: - Providing (S1) a braking device (10) according to one of claims 1 to 9; - Generation (S2) of a redundant braking effect on the front axle (VA) by the first central braking device (BZ1).

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