HYDRAULIC BRAKE SYSTEM AND METHOD FOR OPERATING A BRAKE SYSTEM

Description

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

[0002] Vehicles, especially motor vehicles, typically have a braking system capable of safely braking a moving vehicle to a standstill. Hydraulic braking systems are particularly well-known for this purpose. When applying the brakes, a user can be assisted by a brake booster, such as a vacuum brake booster or an electromechanical brake booster. In addition, assistance systems such as anti-lock braking systems (ABS) or electronic stability programs (ESP) are known, which can actively influence a vehicle's braking behavior.

[0003] The document DE 10 2012 205 861 A1, for example, describes a hydraulic brake system with a master brake cylinder, two brake pressure generators, at least one wheel brake cylinder and interruption means for redundant brake pressure generation and control with electrical assistance.

[0004] DE 10 2011 114 804 A1 discloses a braking system for a vehicle. Disclosure of the invention

[0005] The present invention provides a hydraulic braking system for a vehicle, a motor vehicle having such a hydraulic braking system, and a method for operating a braking system having the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0006] Accordingly, the invention provides: a hydraulic braking system for a vehicle with a pressure build-up device and a driving dynamics control system. The pressure build-up device comprises an input interface, a master brake cylinder, and an electromechanical drive. The input interface of the pressure build-up device is designed to receive an electronic setpoint specification from an external setpoint transmitter. The master brake cylinder is designed to build up hydraulic pressure in at least two independent brake circuits. The electromechanical drive is designed to actuate the master brake cylinder. In particular, the electromechanical drive is designed to actuate the master brake cylinder using the setpoint specification received via the input interface. The master brake cylinder can be actuated exclusively by the electromechanical drive.In other words, no actuating element is provided by which the master brake cylinder can be actuated by an external mechanical actuating element, such as a brake pedal, via a mechanical connection. The vehicle dynamics control system includes a brake pressure generating device. The brake pressure generating device is designed to build up hydraulic pressure in the at least two independent brake circuits. Accordingly, the hydraulic pressure in the two independent brake circuits can be built up by the master brake cylinder on the one hand and by the brake pressure generating device on the other. Furthermore, it is planned:

[0007] A motor vehicle with a hydraulic braking system according to the invention. Finally, it is planned:

[0008] A method for operating a braking system, in particular a hydraulic braking system according to the invention, comprising a step for receiving an electronic setpoint specification at the input interface of the pressure build-up device and a step for controlling the electromechanical drive in accordance with the received setpoint specification. Advantages of the invention

[0009] The present invention is based on the finding that conventional braking systems, particularly hydraulic braking systems, are typically controlled via a mechanical connection from an external mechanical actuating element. For example, this external actuating element can be the brake pedal of a motor vehicle, which is coupled to the master cylinder of a braking system via a mechanical connection. If necessary, this control can be supported by a brake booster. In all cases, however, an external mechanical force, for example from the brake pedal, is transmitted to the master cylinder.

[0010] One idea of ​​the present invention is to replace the mechanical power transmission, for example, from a brake pedal to the master cylinder, with an electronic signal transmission and an electromechanical actuating element on the master cylinder. In this way, complex, time-consuming, and potentially error-prone mechanical power transmissions from a brake pedal to the master cylinder can be avoided and replaced by a simple and flexible electronic signal transmission.

[0011] By using two independent components to provide the hydraulic pressure in the brake circuits, it can be ensured that even if one component for generating the hydraulic pressure fails, sufficient hydraulic pressure can still be built up in the brake circuits to actuate the braking system. The hydraulic braking system of the present invention thus comprises several independent hydraulic brake circuits, so that in the event of a defect in one hydraulic brake circuit, the remaining hydraulic brake circuit(s) still enable the vehicle to be braked.Furthermore, the use of two independent components, each capable of building up hydraulic pressure in the brake circuits, ensures that even if one component fails to build up hydraulic pressure, the other component can still build up sufficient hydraulic pressure to brake the vehicle. In this way, a hydraulic braking system can be implemented that ensures the necessary redundancy and thus safety in the braking system. No mechanical connection is expressly required between a user-operated element, such as a brake pedal, and the braking system. In other words, the setpoint for building up hydraulic pressure in the braking system is determined exclusively by the provision of electronic signals.

[0012] The electronic signal for transmitting the setpoint to the braking system can be generated, transmitted, and provided to the braking system in any way. For example, the signal can be transmitted as a digital signal via a suitable communications bus, such as a CAN bus or similar. Furthermore, the electronic signal can also be provided in the form of a voltage or current signal. In principle, it is also possible, for example, to provide the signal as an optical signal and convert it into an electronic signal at the input interface of the braking system using an appropriate converter.

[0013] The signal for specifying the setpoint can be provided by a setpoint transmitter, for example, a sensor on a brake pedal or similar. In this way, a user can specify a setpoint using a suitable input device, such as the brake pedal, which is then provided to the braking system as an electronic signal via a communication link. Hydraulic pressure can then be built up in the braking system's brake circuits according to the setpoint specified by the user.

[0014] According to one embodiment, the vehicle dynamics control system comprises an electronic stability program (ESP). Accordingly, a component for building up hydraulic pressure in such an ESP can be used to build up hydraulic pressure in the brake circuits of the braking system, for example, in the event of a malfunction of the pressure build-up device with the master brake cylinder. For this purpose, the setpoint specification can also be provided to the vehicle dynamics control system, if necessary, so that the vehicle dynamics control system can build up the desired hydraulic pressure in the event of a defect in the pressure build-up device.

[0015] According to one embodiment, the brake pressure generating device of the vehicle dynamics control system is designed to build up hydraulic pressure in the at least two independent brake circuits if a malfunction has been detected in the pressure buildup device. Accordingly, the vehicle dynamics control system can provide the required hydraulic pressure to actuate the brake system, even if the pressure buildup device cannot provide sufficient hydraulic pressure. Thus, the two independently acting components—on the one hand, the pressure buildup device with the master brake cylinder, and on the other hand, the vehicle dynamics control system with the brake pressure generating device—provide a redundant system for building up hydraulic pressure in the brake circuits.

[0016] According to one embodiment, the braking system comprises a setpoint transmitter. The setpoint transmitter is designed to provide an electronic setpoint specification corresponding to a user input at the input interface of the pressure buildup device. For example, the setpoint transmitter can provide a variable corresponding to a position of a brake pedal. This variable can be provided as an analog or digital signal as a setpoint specification to the pressure buildup device. In addition to the setpoint transmitter, which can detect a position of a brake pedal and provide a corresponding output signal, a feedback device can also be provided on the brake pedal. Such a feedback device can, for example, provide haptic feedback on the brake pedal in the form of a force, vibration, or the like. In this way, a user can be given feedback about the braking behavior.

[0017] According to one embodiment, the setpoint transmitter is mechanically coupled to a brake pedal of the vehicle. Furthermore, the setpoint transmitter is electrically or optically coupled to the input interface of the pressure buildup device. In this way, the variable specified by the user by actuating the brake pedal can be provided as an electrical or optical signal at the input interface of the braking system. Thus, a mechanical coupling of the brake pedal to the braking system can be completely eliminated.

[0018] According to one embodiment, the setpoint specified by the setpoint generator can be provided as a digital data signal at the input interface of the braking system. For example, the variable detected by the setpoint generator can be transmitted to the input interface of the braking system via a data bus, such as a CAN bus or the like.

[0019] According to one embodiment, the pressure buildup device is designed to be powered by a first power supply network. Furthermore, the vehicle dynamics control system is designed to be powered by a second power supply network. In other words, the pressure buildup device and the vehicle dynamics control system are powered by two separate, in particular two independent, power supply networks or energy sources. This ensures that even if one of the two power supply networks fails, sufficient hydraulic pressure can be provided to actuate the braking system. Short description of the drawings

[0020] Further features and advantages of the invention are explained below with reference to the figures. These show: Fig. 1: a schematic representation of a block diagram of a hydraulic braking system according to one embodiment; Fig. 2: a schematic representation of a block diagram of a hydraulic braking system according to another embodiment; and Fig. 3: a flowchart underlying a method for operating a braking system according to one embodiment.

[0021] In the figures, the same reference symbols denote identical or functionally identical components, unless otherwise stated. Description of embodiments

[0022] Figure 1shows a schematic representation of a block diagram to illustrate the basic principle of a hydraulic braking system 1 for a vehicle according to one embodiment. The braking system shown here comprises a pressure build-up device 10 and a driving dynamics control system 20. The pressure build-up device 10 comprises a master brake cylinder 11. This master brake cylinder 11 can have a plurality of chambers 11a, 11b, wherein each chamber 11a, 11b is connected to a separate, independent brake circuit B1, B2. In this way, a hydraulic pressure can be built up in the plurality of independent brake circuits B1, B2 by actuating the master brake cylinder 11. The plurality of brake circuits B1, B2 are not connected to one another in this case. Thus, the plurality of brake circuits B1, B2 are independent brake circuits.In the event of a fault, for example due to a leak, in one of the brake circuits B1, B2, hydraulic pressure can continue to be built up in the remaining brake circuits B1, B2.

[0023] An electromechanical drive 12 is provided for actuating the master brake cylinder 11. In particular, it is intended that the master brake cylinder 11 be actuated exclusively by this electromechanical drive 12. In other words, there is no mechanical coupling of the master brake cylinder to a mechanical actuating element, such as a brake pedal or the like.

[0024] The electromechanical drive 12 can, in principle, be any suitable electromechanical drive, such as an electric motor with a transmission. In particular, the electromechanical drive can be controlled such that, in accordance with a setpoint value received via an input interface 13, a corresponding hydraulic pressure is built up in the brake circuits B1 and B2 by actuating the master brake cylinder 11. For example, an electromechanical drive 12 can be used to actuate the master brake cylinder 11, as is used in the same or similar manner for electromechanical brake boosters of conventional brake systems. According to the invention, however, the conventional mechanical actuation by transmitting a force from the brake pedal to the master brake cylinder is omitted.Rather, the master brake cylinder is actuated exclusively by the electromechanical drive 12 according to the received setpoint value S.

[0025] The setpoint specification S can be received as an analog or digital signal from the input interface 13. For example, an electrical voltage or a corresponding electrical current corresponding to a setpoint specification can be provided at the input interface 13. However, it is also possible to provide a digital signal, for example a pulse-width modulated signal, at the input interface 13. Furthermore, the setpoint specification S can also be provided as digital information via a communication connection, for example a data bus, such as a CAN bus or the like, at the input interface 13. In particular, the setpoint specification S can be provided as an analog or digital electrical signal at the input interface 13.In addition, however, it is also possible, for example, to transmit the setpoint specification as an optical signal and to convert the optical signal into an electrical signal by means of a suitable converter at the input interface 13 and to make it available for further processing.

[0026] The setpoint value S can be provided, for example, by a setpoint transmitter 40. This setpoint transmitter 40 can be, for example, a sensor that provides an output signal that corresponds to a position of a brake pedal or a force exerted on the brake pedal. For this purpose, the setpoint transmitter can be mechanically coupled to the brake pedal, for example. Furthermore, the setpoint transmitter can be connected to the input interface 13 via a communication connection, for example an electrical or optical connection. In this way, a signal that corresponds to the position of the brake pedal can be provided at the input interface 13 of the pressure build-up device 10. Furthermore, additional components that generate feedback at the brake pedal, for example in the form of resistance or vibration, can optionally be provided on the brake pedal.This allows the user to receive haptic feedback about the braking system's braking behavior. This allows the user to simulate the brake pedal's behavior, which corresponds to a direct mechanical coupling between the brake pedal and the master cylinder.

[0027] The pressure build-up device 10 can thus actuate the master brake cylinder 11 using the setpoint provided by the setpoint generator 40 and correspondingly controlling the electromechanical drive 12. This builds up hydraulic pressure in each of the two independent brake circuits B1 and B2. This hydraulic pressure can be used, for example, to actuate the brake elements 31 to 34. These brake elements 31 to 34 can, for example, comprise wheel brake cylinders on the wheels of a vehicle.

[0028] In addition to the pressure build-up device 10, the braking system 1 further comprises a vehicle dynamics control system 20. This vehicle dynamics control system 20 can, for example, be the components of an electronic stability program (ESP). In particular, the vehicle dynamics control system 20 comprises a brake pressure generating device 21. This brake pressure generating device 21 is designed to generate hydraulic pressure in the independent brake circuits B1 and B2. For example, the brake pressure generating device 21 can comprise a hydraulic pump for each brake circuit B1 and B2, which can build up the hydraulic pressure in the brake circuits B1 and B2. In particular, the brake pressure generating device 21 can be an electrically operated brake pressure generating device.

[0029] Such a braking system 1 with a pressure build-up device 10 and a vehicle dynamics control system 20 with a further brake pressure generation device 21 provides two independent components for building up the hydraulic pressure in the independent brake circuits B1 and B2. This provides sufficient redundancy to ensure that the hydraulic pressure required for braking in the brake circuits B1 and B2 can be built up by the other component even if one of the components fails.

[0030] The pressure build-up device 10 with the input interface 13, the electromechanical drive 12, and the master brake cylinder 11 can be supplied with electrical energy, for example, from a first energy supply network 101. The vehicle dynamics control system 20 with the brake pressure generation device 21 can be supplied with electrical energy from a further energy supply network 102. In particular, the first energy supply network 101 and the second energy supply network 102 can be independent of one another. For example, a first electrical energy storage device can be provided in the first energy supply network 101, and a second electrical energy storage device can be provided in the second energy supply network 102.Thus, in the event of a failure of one of the two power supply networks 101 or 102, a redundant power supply is also available for the electrical power supply networks of the braking system 1, in order to supply the components connected to it with electrical power via the remaining power supply network 101 or 102 and thus to be able to provide hydraulic pressure for braking the vehicle. For example, the first power supply network 101 and the second power supply network 102 can be two mutually independent low-voltage direct current networks of a motor vehicle. If necessary, the two power supply networks 101 and 102 can be coupled to one another by means of a DC-DC converter. This enables an energy exchange for charging the electrical energy storage devices in the power supply networks 101 and 102.Furthermore, in particular in the case of fully or at least partially electrically powered vehicles, the pressure build-up device 10 can also be fed directly from a traction battery of such an electric vehicle, while the vehicle dynamics control system 20 is fed with electrical energy from a low-voltage network.

[0031] In order to be able to build up a hydraulic pressure in a controlled manner according to the setpoint value S even in the event of a malfunction of the pressure buildup device 10, the setpoint value S can also be additionally provided to the vehicle dynamics control system 20 and in particular to the brake pressure generating device 21. In this case, upon detection of a malfunction of the pressure buildup device 10, the brake pressure generating device 21 of the vehicle dynamics control system 20 can build up a brake pressure in the brake circuits B1 and B2 that corresponds to the setpoint value S.

[0032] Figure 2shows a schematic representation of a block diagram of a braking system 1 according to an embodiment. The following also applies to the braking system 1 according to Figure 2 which were previously associated with Figure 1 In addition, Figure 2 the individual components of the pressure build-up device 10 and the driving dynamics control 20 are shown in more detail.

[0033] For example, in Figure 2As can be seen, the individual chambers 11a and 11b of the master brake cylinder 11 can be fed from a reservoir 15. In the idle state, i.e. when the master brake cylinder 11 is not actuated, a direct flow of brake fluid from the reservoir 15 through the chambers 11a and 11b of the master brake cylinder 11 into the brake circuits B1 and B2 is possible. Preferably, a device is provided in the master brake cylinder 11 which, in the idle state, moves the piston of the master brake cylinder 11 into a position in which such an unhindered flow of brake fluid from the reservoir 15 into the two independent brake circuits B1 and B2 is possible. This can be achieved, for example, by means of spring force or the like.In this way, it can be ensured that in the event of a malfunction or failure of the electromechanical drive 12, the brake fluid can flow from the reservoir 15 into the brake circuits B1 and B2, thus allowing sufficient hydraulic pressure to be built up by the brake pressure generating device 21 of the vehicle dynamics control system 20. Furthermore, the master brake cylinder 11 can also be configured such that, even when the master brake cylinder 11 is activated, a flow of hydraulic fluid from the reservoir 15 toward the vehicle dynamics control system 20 and, in particular, the brake pressure generating device 21 is possible.

[0034] As already briefly mentioned above, the vehicle dynamics control 20 may be an electronic stability program (ESP) or similar. The individual components of such an ESP are shown schematically in Figure 2However, to the extent that these are not the subject of the present invention, they will not be explained in detail here.

[0035] The vehicle dynamics control system 20 and in particular the ESP comprise, in addition to other components, a brake pressure generating device 21. For example, this can be a hydraulic pump which, by means of an electric motor, can generate a hydraulic pressure for actuating the brake elements 31 to 34. In particular, the brake pressure generating device 21 of the vehicle dynamics control system 20 can generate a hydraulic pressure in each of the independent brake circuits B1 and B2. For this purpose, independent components for generating the hydraulic pressure can be provided in the individual brake circuits B1 and B2. Alternatively, it is also possible that, as in Figure 2 shown, the pump components for building up the hydraulic pressure are controlled by a common electric drive.

[0036] The components for the brake pressure generation device 21 of the vehicle dynamics control system 20 can, in principle, be components that are also used in conventional vehicle dynamics control systems, in particular ESP. Furthermore, the components for generating the hydraulic pressure can, if necessary, also be dimensioned accordingly to increase redundancy for a fully electronically actuated braking system.

[0037] Figure 3 shows a flowchart underlying a method for operating a hydraulic brake system according to one embodiment. The brake system 1 operated here can, in particular, be one of the previously described hydraulic brake systems 1.

[0038] In step S1, an electronic setpoint value is received at the input interface 13 of the pressure build-up device 10.

[0039] Subsequently, in step S2, the electromechanical drive 12 can be controlled according to a received setpoint value S.

[0040] If, due to a defect or malfunction, it is not possible for the pressure build-up device 10 to provide the required hydraulic pressure to actuate the braking system, the hydraulic pressure can alternatively be built up by the brake pressure generation device 21 of the vehicle dynamics control system 20. This provides sufficient redundancy for the safe operation of the hydraulic braking system in a vehicle.

[0041] In summary, the present invention relates to a hydraulic braking system, in particular a hydraulic braking system for a motor vehicle. In this system, the control of a master brake cylinder to build up hydraulic pressure is carried out exclusively by an electric drive. The setpoint value for controlling the electromechanical drive can be received as an electrical signal. By using a brake pressure generation device of a vehicle dynamics control system, redundant brake pressure generation can be ensured in the event of a fault.

Claims

1. Hydraulic brake system (1) for a vehicle, comprising: a pressure build-up device (10) and a vehicle dynamics control system (20), wherein the pressure build-up device (10) comprises: an input interface (13), which is designed to receive an electronic setpoint value specification (S) from an external setpoint value generator (40), a master brake cylinder (11), which is designed to build up hydraulic pressure in at least two independent brake circuits (B1, B2), and an electromechanical drive (12), which is designed to actuate the master brake cylinder (11) using the setpoint value specification (S) received by the input interface (13), wherein the master brake cylinder (11) can be actuated only by the electromechanical drive (12); characterized in that the vehicle dynamics control system (20) comprises a brake pressure generating device (21), which is designed to build up hydraulic pressure in the at least two independent brake circuits (B1, B2).

2. Brake system (1) according to Claim 1, wherein the vehicle dynamics control system (20) comprises an electronic stability program.

3. Brake system (1) according to Claim 1 or 2, wherein the brake pressure generating device (21) of the vehicle dynamics control system (20) is designed to build up a hydraulic pressure in the at least two independent brake circuits (B1, B2) if a malfunction has been detected in the pressure build-up device (10).

4. Brake system (1) according to any of Claims 1 to 3, comprising a setpoint value generator (40), which is designed to provide an electronic setpoint value specification (S), which corresponds to a user input, at the input interface (13) of the pressure build-up device (20).

5. Brake system (1) according to Claim 4, wherein the setpoint value generator (40) is mechanically coupled to a brake pedal of the vehicle, and wherein the setpoint value generator (40) is electrically coupled to the input interface (13) of the pressure build-up device (10).

6. Brake system (1) according to Claim 4 or 5, wherein the setpoint value generator (40) is coupled to the input interface (13) of the pressure build-up device (10) via a digital communication interface.

7. Brake system (1) according to any of Claims 1 to 6, wherein the pressure build-up device (10) is designed to be fed by a first power supply system (101), and wherein the vehicle dynamics control system (20) is designed to be fed by a second power supply system (102).

8. Motor vehicle having a hydraulic brake system (1) according to any of Claims 1 to 7.

9. Method for operating a brake system (1) according to any of Claims 1 to 7, characterized in that the method comprises the steps of: receiving (S1) an electronic setpoint value specification (S) at the input interface (13) of the pressure build-up device (10); and controlling (S2) the electromechanical drive (12) in accordance with the received setpoint value specification (S).

10. Method according to Claim 9, comprising a step for building up a hydraulic pressure in at least one of the brake circuits (B1, B2) by means of the brake pressure generating device (21) of the vehicle dynamics control system (20) if a malfunction has been detected in the pressure build-up device (10).