Brake system with brake-by-wire design and vehicle

Abstract

The invention relates to a brake system (20) for a brake-by-wire design of a vehicle, comprising a control unit (26), a brake pedal (32) and an electronic brake device (28) which is coupled to the brake pedal (32) and which is provided for actuating a brake mechanism (14) of the vehicle (10). The brake system (20) has a hydraulic brake device (30) which is coupled to the brake pedal (32) in parallel to the electronic brake device (28) and which is provided for hydraulically actuating the brake mechanism (14). The brake system (20) has a main operating mode and an emergency operating mode. The invention further relates to a vehicle having such a brake system (20).

Description

Technical Field

[0001] The present invention relates to a braking system for a vehicle with a brake-by-wire design, the braking system including a control unit, a brake pedal, and an electronic braking device coupled to the brake pedal, the electronic braking device being arranged to operate a braking mechanism of the vehicle. Furthermore, the present invention also relates to a vehicle having such a braking system. Background Art

[0002] Braking systems with a brake-by-wire design and vehicles equipped with such braking systems are known.

[0003] Different from traditional braking systems in which the brakes of a vehicle are hydraulically controlled, in so-called brake-by-wire systems the brakes are no longer directly hydraulically controlled, but rather controlled by electrical pulses and a motor controlled by a microprocessor.

[0004] Since the brakes are safety-critical components, the brakes must meet strict safety requirements. Regarding brakes directly hydraulically controlled, many safety mechanisms and safety protection measures are known, especially because of their standardized application in vehicle manufacturing. However, for brake-by-wire systems, similar safeguard solutions are unknown in the prior art, especially for emergency operation after at least a part of the brake-by-wire system fails. Summary of the Invention

[0005] The object of the present invention is to provide a braking system with a brake-by-wire design that provides reliable emergency operation. Furthermore, the object of the present invention is to provide a vehicle having such a braking system.

[0006] The first-mentioned object is solved by a braking system for a vehicle with a brake-by-wire design, the braking system including a control unit, a brake pedal, and an electronic braking device coupled to the brake pedal, the electronic braking device being arranged to operate a braking mechanism of the vehicle. The braking system hereby has a hydraulic braking device that is coupled to the brake pedal in parallel with the electronic braking device and that is arranged to hydraulically operate the braking mechanism. Furthermore, the braking system has a main operation mode and an emergency operation mode, in the main operation mode the hydraulic braking device is hydraulically decoupled from the braking mechanism, and in the emergency operation mode the hydraulic braking device is hydraulically coupled to the braking mechanism.

[0007] It has been recognized according to the present invention that when the electronic braking device fails, the vehicle can be reliably decelerated and stopped by means of the hydraulic braking device. The hydraulic braking device thus constitutes an emergency braking system for the vehicle. Since both the electronic braking device and the hydraulic braking device can be operated by a common brake pedal, the driver can always operate the braking mechanism in the same way, namely by means of the brake pedal, whereby the braking system is particularly comfortable and reliable.

[0008] In one embodiment, the braking system is configured to operate the brake mechanism in a main operating mode by means of an electronic braking device (instead of by means of a hydraulic braking device) in accordance with an operation of the brake pedal, and to hydraulically operate the brake mechanism in an emergency operating mode by means of a hydraulic braking device (instead of by means of an electronic braking device) in accordance with the operation of the brake pedal. In the main operating mode, the braking system thus operates in a pure-by-wire braking mode, that is to say, the brake mechanism is controlled by electrical pulses and a motor controlled by a microprocessor, instead of being controlled by a hydraulic braking device which is hydraulically decoupled from the brake mechanism in this mode.

[0009] In another embodiment, the hydraulic braking device has a hydraulic cylinder which is coupled to the brake pedal such that when the brake pedal is operated, the hydraulic cylinder is operated (in particular in a similar manner). "In a similar manner" in the sense of the present invention here means that the hydraulic cylinder is not operated digitally, such as by means of a motor controlled by a microprocessor. Additionally or alternatively, "in a similar manner" means that when the brake pedal is operated, the hydraulic cylinder is moved in a manner corresponding to and together with the brake pedal. In this way, it is ensured that the hydraulic braking device can be reliably and definably operated in the emergency operating mode.

[0010] Furthermore, it can be provided here that the hydraulic braking device has a valve which has a first position and a second position. In the first position, the hydraulic cylinder is hydraulically connected to the reservoir of the hydraulic braking device, instead of to the brake mechanism, while in the second position, the hydraulic cylinder is hydraulically connected to the brake mechanism. The valve is in the first position in the main operating mode and in the second position in the emergency operating mode. Thus, in the main operating mode, when the brake pedal is operated, the hydraulic fluid will be displaced into the reservoir. Thereby, the additional resistance provided by the hydraulic braking device is particularly small, such that the brake pedal can be operated similarly in the main mode compared to a braking system without a hydraulic braking device.

[0011] In particular, the valve can be designed such that it is in the first position in the energized state and in the second position in the non-current state. Thus, it is ensured that when the vehicle electrical system fails, the valve is in the second position and thus the hydraulic cylinder is hydraulically connected to the braking device.

[0012] According to the invention, to solve the above-mentioned task, a vehicle is also provided which has a braking system, a brake and a drive train with a drive motor according to the invention having the aforementioned advantages. The electronic braking device is here configured to operate the brake in a main operating mode in accordance with an operation of the brake pedal.

[0013] According to one embodiment, the brake forms a braking mechanism and a hydraulic braking device is provided for hydraulically operating the brake in an emergency operation mode in accordance with an operation of a brake pedal. This embodiment has the advantage that the braking mechanism can be designed particularly compactly.

[0014] In an alternative embodiment, the vehicle has a drive train brake. The hydraulic braking device is coupled to the drive train via the drive train brake in this case. Thus, in addition to the brakes that are usually coupled to the vehicle wheels, the vehicle also has a drive train brake by means of which the drive train or the motor can be braked. In this way, the safety of the braking system is increased.

[0015] Here, the brake and the drive train brake can each form part of a braking mechanism. Here, the hydraulic braking device is provided for hydraulically operating the brake and the drive train brake in an emergency operation mode in accordance with an operation of the brake pedal. Thus, even if the brake or the drive train brake fails, the vehicle can be reliably decelerated.

[0016] Alternatively, the drive train brake can be part of the braking mechanism or form the braking mechanism. In this case, the hydraulic braking device is provided for hydraulically operating the drive train brake in an emergency operation mode in accordance with an operation of the brake pedal. In this way, a connection between the hydraulic braking system and the brake is not required, since the coupling between the hydraulic braking device and the drive train ensures the necessary safety. Thus, even in the case of a complete failure of the electronic device and thus a complete failure of the electronic braking device, the vehicle can be reliably brought to a standstill. This embodiment also has the advantage that the space requirement for coupling the hydraulic braking device to the drive train is smaller compared to an embodiment in which the hydraulic braking device is coupled to the brakes (especially when the brakes include wheel brakes for each wheel of the vehicle).

[0017] Furthermore, it can be provided that the drive train brake acts on the drive shaft of the drive motor or is directly coupled to the drive shaft of the drive motor. Thereby, the vehicle is designed particularly compactly. Description of the Drawings

[0018] Other advantages and features result from the following description and the drawings. The drawings are as follows:

[0019] Figure 1 A vehicle according to the invention having a braking system and a drive train according to the invention is shown schematically;

[0020] Figure 2 Is shown schematically Figure 1 the braking system in

[0021] Figure 3 Is shown schematicallyFigure 1 the drive train therein; and

[0022] Figure 4 shows schematically another embodiment of a drive train according to Figure 1 thereof. DETAILED DESCRIPTION

[0023] In Figure 1 is shown a vehicle 10 having a drive train 12, a brake mechanism 14 and a brake system 20.

[0024] In the present embodiment, the drive train 12 includes a drive motor 16 in the form of an electric motor (see Figure 3 ). Accordingly, the vehicle 10 is an electric vehicle.

[0025] In principle, the vehicle 10 can be any motor vehicle, such as a hybrid vehicle.

[0026] The brake mechanism 14 has a brake 18 which is part of the service braking equipment of the vehicle 10 and has wheel brakes 22 for each wheel 24 of the vehicle 10.

[0027] The brake system 20 is a brake-by-wire system and includes a control unit 26 (see Figure 2 ) and an electronic brake device 28 and a hydraulic brake device 30 which are connected to the control unit 26 in a signal-transmitting manner.

[0028] Furthermore, the brake system 20 has a brake pedal 32 which is arranged to operate the brake mechanism 14 and is movably fixed to a body part of the vehicle 10 in a known manner for this purpose, for example pivotable about a pivot axis.

[0029] The brake pedal 32 is coupled to a spring 34 which loads the brake pedal 32 into a neutral or initial position in which the brake pedal 32 is not operated.

[0030] The electronic brake device 28 is arranged to operate the brake 18 according to the operated position of the brake pedal 32 and for this purpose has a pedal sensor 36 which is arranged to detect the position of the brake pedal 32.

[0031] The hydraulic brake device 30 has a hydraulic cylinder 38, a reservoir 40 and a first hydraulic line 42 and a second hydraulic line 44. The hydraulic cylinder 38 is hydraulically connected to the reservoir 40 by means of the first hydraulic line, and the hydraulic cylinder 38 is hydraulically connected to the brake mechanism 14 by means of the second hydraulic line.

[0032] In this case, the brake pedal 32 is coupled to the hydraulic cylinder 38 such that when the brake pedal 32 is operated, the hydraulic cylinder 38 is operated in a manner similar to the brake pedal 32. In other words, when the brake pedal 32 moves, the piston of the hydraulic cylinder 38 also moves.

[0033] In this way, the hydraulic braking device 30 is coupled to the brake pedal 32 in parallel with the electronic braking device 28 via the hydraulic cylinder 38.

[0034] The hydraulic braking device 30 also has a valve 46 which is connected to the control unit 26 in a signal-transmitting manner and is movable between a first position and a second position.

[0035] In the first position, the hydraulic cylinder 38 is hydraulically connected to the reservoir 40 via a first hydraulic line 42, while the hydraulic cylinder 38 is hydraulically decoupled from the brake mechanism 14.

[0036] In the second position, the hydraulic cylinder 38 is hydraulically connected to the brake mechanism 14 via a second hydraulic line 44, while the hydraulic cylinder 38 is hydraulically decoupled from the reservoir 40.

[0037] The braking system 20 has a main operating mode (in which the valve 46 is in the first position) and an emergency operating mode (in which the valve 46 is in the second position).

[0038] The main operating mode constitutes the normal operating mode here, in which the brake 18 is operated by means of the electronic braking device 28 rather than the hydraulic braking device 30.

[0039] Conversely, when the main operating mode is not available, for example when the pedal sensor 36 or the electronics of the electronic braking device 28 fail, the emergency operating mode is activated.

[0040] In this emergency or special situation, the brake mechanism 14 is operated by means of the hydraulic braking device 30 in the emergency operating mode.

[0041] Here, the hydraulic braking device 30 can be arranged to operate the brake 18 in the emergency operating mode.

[0042] In this case, the valve 46 is constructed such that the valve (for example by means of a spring element) is preloaded into the second position. Thereby, in the emergency or special situation, it is ensured that the hydraulic cylinder 38 is hydraulically connected to the brake mechanism 14 in the emergency operating mode. In the normal operating mode, the valve 46 is held in the first position (for example by means of an electromagnet).

[0043] In another embodiment, the vehicle 10 has a drive train brake 48 (see Figure 3), the drive train brake acts directly on the drive shaft 50 of the drive motor 16. Thus, when the drive train brake 48 is operated, the drive motor 16 can be directly braked via the drive shaft 50.

[0044] In Figure 3 the illustrated embodiment, the drive train brake 48 has a brake disc 52 (which is non-rotatably connected to the drive shaft 50) and brake shoes 54, and when the drive train brake 48 is operated, the brake shoes are pressed against the brake disc 52 with a force F in the axial direction.

[0045] In an alternative embodiment (see Figure 4 ), the drive train brake has brake shoes 54 which, when the drive train brake 48 is operated, are pressed against the brake disc 52 with a force F in the radial direction.

[0046] In embodiments in which the vehicle 10 has a drive train brake 48, the hydraulic braking device 30 is coupled to the drive train brake 48 in order to directly brake the drive train 12 in an emergency operation mode.

[0047] Here, in one embodiment, the hydraulic braking device 30 can be coupled not only to the brake 18 but also to the drive train brake 48, so that in the emergency operation mode, when the brake pedal 32 is operated, the hydraulic braking device 30 brakes the vehicle 10 by means of the brake 18 and the drive train brake 48.

[0048] In this embodiment, the brake 18 and the drive train brake 48 each form part of the braking mechanism 14.

[0049] In an alternative embodiment, the hydraulic braking device 30 is only coupled to the drive train brake 48, so that in the emergency operation mode, when the brake pedal 32 is operated, the hydraulic braking device 30 brakes the vehicle 10 only via the drive train brake 48.

[0050] In this embodiment, the drive train brake 48 forms the braking mechanism 14, while the brake 18 is not part of the braking mechanism 14.

[0051] In all embodiments, a vehicle 10 and a braking system 20 are provided in such a way that the vehicle and the braking system can operate reliably and safely even when the electronic braking device 28 fails.

[0052] The invention is not limited to the illustrated embodiments. In particular, the features of one embodiment can be arbitrarily combined with the features of other embodiments, especially independently of the other features of the respective embodiments.

Claims

1. A braking system (20) for a by-wire braking design of a vehicle (10), the braking system comprising a control unit (26), a brake pedal (32) and an electronic braking device (28) coupled to the brake pedal (32), the electronic braking device being arranged to operate a braking mechanism (14) of the vehicle (10), characterized in that, The braking system (20) has a hydraulic braking device (30) which is coupled to a brake pedal (32) in parallel with an electronic braking device (28) and which is designed to operate a braking mechanism (14) hydraulically. The braking system (20) has a main operating mode and an emergency operating mode. In the main operating mode, the hydraulic braking device (30) is hydraulically decoupled from the braking mechanism (14), and in the emergency operating mode, the hydraulic braking device (30) is hydraulically coupled to the braking mechanism (14).

2. The braking system (20) according to claim 1, characterized in that, The braking system (20) is designed to operate the braking mechanism (14) by means of the electronic braking device (28), rather than by means of the hydraulic braking device (30), depending on the operation of the brake pedal (32) in the main operating mode, and to operate the braking mechanism (14) hydraulically by means of the hydraulic braking device (30), rather than by means of the electronic braking device (28), depending on the operation of the brake pedal (32) in the emergency operating mode.

3. The braking system (20) according to claim 1 or 2, characterized in that, The hydraulic braking device (30) has a hydraulic cylinder (38) which is coupled to the brake pedal (32) such that the hydraulic cylinder is operated, in particular in a similar manner, when the brake pedal (32) is operated.

4. The braking system (20) according to claim 3, characterized in that, The hydraulic braking device (30) has a valve (46) which has a first position and a second position. In the first position, the hydraulic cylinder (38) is hydraulically connected to a reservoir (40) of the hydraulic braking device (30), rather than to the braking mechanism (14), and in the second position, the hydraulic cylinder (38) is hydraulically connected to the braking mechanism (14). The valve (46) is in the first position in the main operating mode and in the second position in the emergency operating mode. In particular, the valve (46) is designed such that it is in the first position in the energized state and in the second position in the currentless state.

5. A vehicle (10) comprising a braking system (20), a brake (18) and a drive train (12) with a drive motor (16) according to any one of the preceding claims, wherein, The electronic braking device (28) is designed to operate the brake (18) depending on the operation of the brake pedal (32) in the main operating mode.

6. The vehicle (10) according to claim 5, characterized in that, The brake (18) forms the braking mechanism (14) and the hydraulic braking device (30) is designed to operate the brake (18) hydraulically depending on the operation of the brake pedal (32) in the emergency operating mode.

7. The vehicle (10) according to claim 5, characterized in that, The vehicle (10) has a drive train brake (48) via which the hydraulic braking device (30) is coupled to the drive train (12).

8. The vehicle (10) according to claim 7, characterized in that, The brake (18) and the drive train brake (48) each form part of the braking mechanism (14), and the hydraulic braking device (30) is designed to operate the brake (18) and the drive train brake (48) hydraulically depending on the operation of the brake pedal (32) in the emergency operating mode.

9. The vehicle (10) according to claim 7, characterized in that, The drive train brake (48) is part of or forms the braking mechanism (14), and the hydraulic braking device (30) is designed to operate the drive train brake (48) hydraulically depending on the operation of the brake pedal (32) in the emergency operating mode.

10. The vehicle (10) according to any one of claims 7 to 9, characterized in that, The drive train brake (48) acts on the drive shaft (50) of the drive motor (16) or is directly coupled to the drive shaft (50) of the drive motor (16).

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