Method and braking system for braking a vehicle

Abstract

The present invention relates to a method (M) for braking a vehicle, comprising: detecting (M1) a braking expectation signal representing a target deceleration of the vehicle; generating (M21) a hydraulic braking pressure in a wheel brake cylinder (1) by means of a first pressure generating device (10) hydraulically connected to the wheel brake cylinder (1) based on the detected braking expectation signal; detecting (M3) a fault condition of the first pressure generating device (10); if a fault condition of the first pressure generating device (10) is detected, obtaining (M4) an alternative braking expectation signal, wherein the alternative braking expectation signal is obtained based on a target deceleration known at a predetermined time point before the fault condition is detected; and generating (M5) an alternative braking pressure in the wheel brake cylinder (1) by means of a braking pressure regulating device (120) having a second pressure generating device (20) hydraulically coupled to the wheel brake cylinder based on the obtained alternative braking expectation signal. Furthermore, the present invention relates to a method (M) for braking a vehicle, wherein the alternative braking desired signal is obtained based on a target deceleration known at a predetermined time point before a fault condition is detected, and based on the braking torque generated by a motor dynamically coupled to the wheels of the vehicle. Another aspect of the invention relates to a braking system (100) for a vehicle.

Description

Technical Field

[0001] The present invention relates to a method for braking a vehicle and a braking system for a vehicle. Background Technology

[0002] Typical hydraulic braking systems are used in road vehicles such as passenger cars or trucks. These systems increasingly operate based on the principle of "brake-by-wire," where sensors detect the operation of the brake pedal and determine the desired braking force, representing the desired deceleration of the vehicle. The hydraulic pressure is then determined from the braking force and generated in wheel brake cylinders for braking the vehicle's wheels by means of a pressure generating device, such as an electrically driven plunger.

[0003] In addition, road vehicle braking systems typically have brake pressure regulating devices for individualized wheel brake pressure regulation, in order to perform, for example, anti-lock braking systems (ABS). Typically, such brake pressure regulating devices have their own pressure generating devices and valve assemblies for individualized wheel pressure changes.

[0004] In a braking system that operates on the principle of brake-by-wire, when the pressure generating device malfunctions, the master brake cylinder, which can be operated via the brake pedal, is typically hydraulically connected to the wheel brake cylinders, allowing the necessary braking pressure to be generated manually.

[0005] DE 102014225954 A1 describes a braking system in which a brake pressure regulating device is configured to generate wheel-individualized brake pressure, and assumes the responsibility of generating the desired brake pressure when an externally controlled first pressure generating device fails. Summary of the Invention

[0006] According to the present invention, a method for braking a vehicle, a braking system are provided.

[0007] According to a first aspect of the invention, a method for braking a vehicle is provided. The method includes: detecting, for example, a braking expectation signal representing a target deceleration of the vehicle based on the operation of a braking control device; generating hydraulic braking pressure in a wheel brake cylinder by means of a first pressure generating device, the first pressure generating device being hydraulically connected to the wheel brake cylinder, based on the detected braking expectation signal; detecting a fault condition of the first pressure generating device; when a fault condition of the first pressure generating device is detected, obtaining an alternative braking expectation signal, wherein the alternative braking expectation signal is obtained based on a target deceleration known at a predetermined time point prior to the detection of the fault condition; and generating an alternative braking pressure in the wheel brake cylinder by means of a braking pressure regulating device, the braking pressure regulating device having a second pressure generating device hydraulically coupled to the wheel brake cylinder, based on the obtained alternative braking expectation signal.

[0008] According to a second aspect of the invention, a method for braking a vehicle includes: detecting, for example, a braking expectation signal representing a target deceleration of the vehicle based on the operation of a braking control device; generating a braking torque based on the braking expectation signal by means of a motor kinematically coupled to the wheels of the vehicle; preparing a first pressure generating device hydraulically connected to a wheel brake cylinder for generating braking pressure in the wheel brake cylinder based on the braking expectation signal; detecting a fault state of the first pressure generating device; when a fault state of the first pressure generating device is detected, obtaining an alternative braking expectation signal, wherein the alternative braking expectation signal is obtained based on a target deceleration known at a predetermined time point before the fault state is detected and based on the braking torque generated by the motor; and generating an alternative braking pressure in the wheel brake cylinder based on the obtained alternative braking expectation signal by means of a braking pressure regulating device having a second pressure generating device hydraulically coupled to the wheel brake cylinder.

[0009] According to a third aspect of the present invention, a braking system for a vehicle is provided. The braking system includes: a sensor for detecting braking desire or a braking desire signal; a wheel brake cylinder for generating frictional force at the wheels of the vehicle; a first pressure generating device hydraulically coupled to the wheel brake cylinder and configured to generate hydraulic pressure in the wheel brake cylinder; a brake pressure regulating device having a second pressure generating device hydraulically coupled to the wheel brake cylinder and configured to generate hydraulic pressure in the wheel brake cylinder independently of the first pressure generating device; and a control system signal-connected to the actuator sensor, the first pressure generating device, and the brake pressure regulating device and configured to cause the braking system to perform the method according to the first aspect of the present invention. In performing the method according to the third aspect of the present invention, the control system is particularly capable of having an interface for connection to an electric motor.

[0010] One of the concepts underlying this invention is to compensate for a malfunction of a pressure generating device in a braking system by incorporating a brake pressure regulating device, for example, a device for implementing ABS or ESP functions. In this braking system, hydraulic braking pressure is generated by a pressure generating device that is externally operated or not kinematically coupled to the braking control device (e.g., brake pedal or brake lever). Upon detecting a malfunction or fault condition in the pressure generating device, the brake pressure regulating device initially sets a braking pressure corresponding to a braking pressure known before the malfunction was detected, or equivalent to the braking torque generated by a motor. That is, instead of relying on the detection of a braking expectation signal, for example, generated by the driver, the braking pressure is automatically set first, corresponding to a desired target deceleration known at a defined, past point in time. Therefore, this alternative braking pressure is generated solely based on the sought or correspondingly generated alternative braking expectation signal, which can be constant, at least within a predetermined time period. In this case, the present invention can be used not only for purely hydraulic braking (in which braking torque is generated partly by a motor operating as a generator and partly hydraulically or by means of wheel brake cylinders) but also for purely regenerative braking (in which braking torque is initially generated entirely by a motor operating as a generator). In the last mentioned case, or according to the second aspect of the invention, a first pressure generating device is prepared for subsequent intervention, for example, as a backup or supplementary solution. If the first pressure generating device fails during purely regenerative braking before it generates braking pressure in the wheel brake cylinders, regenerative braking is terminated, and the brake pressure regulating device generates braking pressure in the wheel brake cylinders based on the last effective braking torque generated by the motor before the failure of the first pressure generating device.

[0011] Generally, if the pressure generating device is no longer able to set the desired braking pressure, a fault condition of the first pressure generating device, such as a plunger driven by an electric motor, can be detected. This could be, for example, the pressure generating device itself malfunctioning due to overheating or other damage to the electric motor, or the pressure generating device not receiving an actuation signal. The latter situation could occur, for example, when the detection of the desired braking signal ceases to function, or when, for example, the determination of the braking pressure by means of a control unit ceases to function.

[0012] The advantage of this invention is that, after a failure of the first pressure generating device, braking pressure can be immediately generated by a second pressure generating device of the braking pressure regulating device based on the braking expectation known before the failure. That is, it is not necessary to first wait for the driver's reaction, which could be, for example, additionally pressing the brake pedal or additionally pulling the brake lever. Therefore, the braking distance can be advantageously shortened.

[0013] Advantageous design and modification schemes can be obtained by referring to the accompanying drawings in the instruction manual.

[0014] According to some implementations, the detection of the desired braking signal can include the detection of the operation of the braking control device. For example, the adjustment stroke of the brake pedal or brake lever can be detected by means of a control sensor, wherein a desired braking signal is generated based on the detected adjustment stroke. Other types of control detection are also conceivable, such as detecting the pressure generated in a simulator by operating the braking control device. Generally, the detection of the desired braking signal can be achieved based on the operation of the braking control device.

[0015] According to some implementations, the determination of the alternative braking expectation signal can include determining the adjustment stroke of the brake control device at a predetermined time point before a fault condition is detected. As already explained, the adjustment stroke of the brake control device (e.g., pedal or lever) can be determined, in particular, by means of an adjustment stroke sensor. The determined adjustment stroke can be detected in a time-resolved manner, and the detected value can be stored for a predetermined, especially variable (gleitend) time period, so that even if the adjustment stroke sensor and / or the first pressure generating device fails, the last valid value can be used, which is then considered for determining the alternative braking expectation. This further improves reliability.

[0016] According to some implementations, the acquisition of the alternative braking expectation signal can include acquiring the braking pressure in the wheel brake cylinder at a predetermined time point before a fault condition is detected. For example, the pressure can be detected, particularly in a time-resolved manner, by means of a sensor in the hydraulic path connecting the first pressure generating device to the wheel brake cylinder. The detected values ​​can be stored within a predetermined, particularly variable, time period, so that even if the first pressure generating device fails, the last valid value can be used, and this last valid value is then considered in acquiring the alternative braking expectation. Reliability is further improved in this way.

[0017] According to some embodiments, the method can include generating braking torque based on a desired braking signal, using a motor kinematically coupled to the vehicle's wheels. This can be advantageous, for example, in electrically driven or hybrid vehicles, where the desired target deceleration is achieved partly by the operation of the motor as a generator and partly by means of wheel brake cylinders. Therefore, the braking pressure of the hydraulic fluid generated in the wheel brake cylinders by a first pressure generating device and / or a second pressure generating device is also related to the proportion of the target deceleration provided by the motor.

[0018] According to some implementation methods, it is possible to determine an alternative braking torque based on the braking torque generated by the motor. For example, the motor control unit, such as power electronics, can output a machine control signal representing the braking torque generated by the motor to the control system of the hydraulic braking system, which determines, based on this machine control signal, what kind of braking torque must be generated by the friction brake cylinder.

[0019] In some embodiments, the brake pressure regulating device can be configured to have a first control unit that operates a second pressure generating device, wherein a fault condition of the first pressure generating device is detected based on a control signal sent to the first control unit. For example, a fault condition can be identified if a control signal is missing or if a fault signal is sent to the first control unit instead of a control signal. The first control unit can particularly have a processor unit and a data memory, wherein the processor unit has, for example, one or more CPUs, FPGAs, ASICs, etc., and the data memory is particularly non-volatile data memory, such as HDD memory or SSD memory. For example, software can be stored in the data memory, which can be implemented by the processor unit to output output signals, especially operating signals, to the second pressure generating device and optionally to a valve to operate the valve. The output signals can be generated, for example, based on control signals and / or based on pressure signals representing the current pressure acting on the suction side of the second pressure generating device. The first control device can, for example, be configured to cause the pressure generating device to cooperate with the valve assembly when necessary to perform anti-lock braking function and / or wheel-specific changes in brake pressure.

[0020] In some implementations, a second control unit can be configured to operate a first pressure generating device based on a braking expectation signal, wherein the second control unit generates a first control signal and sends it to the first control unit. The second control unit can, in particular, have a processor unit and a data memory, wherein the processor unit has, for example, one or more CPUs, FPGAs, ASICs, etc., and the data memory is particularly non-volatile data memory, such as HDD memory or SSD memory. Software, for example, can be stored in the data memory and implemented by the processor unit to output output signals, particularly control signals, to the first pressure generating device and optionally to a valve to operate the valve. The second control unit can, for example, determine the braking pressure based on the braking expectation signal and operate the first pressure generating device accordingly, the braking expectation signal being output, for example, through an adjustment stroke sensor coupled to the braking control device. The second control device can, for example, report the determined braking pressure, the adjustment stroke of the braking control device, or other parameters proportional to the target deceleration in a control signal to the first control device. Optionally, the first control device can store the control signals obtained from the second control device in its data memory within a defined, variable time period, so that the stored values ​​can be used in the event of a failure of the pressure generating device, so that the alternative braking desired signal can be obtained more easily.

[0021] According to some implementations, the generation of alternative braking pressure can include generating a linear, stepwise, and / or gradually increasing or gradually decreasing pressure rise in the wheel brake cylinder.

[0022] According to some implementations, it can be configured such that, by operating the brake control device (which, as already explained, can be, for example, a brake pedal or brake lever), hydraulic reset pressure is generated in the reset simulator by means of the master brake cylinder, wherein, if a malfunction of the first pressure generating device is detected, the master brake cylinder is hydraulically coupled to the wheel brake cylinders, and the first pressure generating device is preferably hydraulically disengaged from the wheel brake cylinders. The master brake cylinder can be hydraulically connected to and disengaged from the wheel brake cylinders, for example, via a first release valve. The first pressure generating device can be similarly hydraulically connected to and disengaged from the wheel brake cylinders via a second release valve. If the first pressure generating device is operational, the first release valve is closed, and the master brake cylinder, kinematically coupled to the brake control device, is thus hydraulically disengaged from the wheel brake cylinders. In the event of a malfunction of the first pressure generating device, the first release valve is opened and optionally the second release valve is closed. Thus, the master brake cylinder is hydraulically connected to the wheel brake cylinders. This results in the driver no longer feeling only the reset force of the simulator at the brake control device, but rather feeling actual braking pressure. Furthermore, the opening of the first release valve causes a shift in flow from the wheel brake cylinders to the master brake cylinder, resulting in a decrease in brake pressure. This needs to be compensated for by the driver through further manipulation of the brake control mechanism, such as by additionally pressing the brake pedal. However, because the brake pressure regulating device according to the invention can fully absorb the pressure generation and set the final known brake pressure, at least in a transitional manner, it provides the driver with more time to react, which advantageously improves operating comfort and safety.

[0023] According to some implementations, an alternative braking pressure can be generated based on a desired alternative braking signal during a predetermined first time period, and this desired alternative braking signal subsequently decreases linearly to zero during a transition period. During this transition period, the alternative braking pressure is generated by means of a braking pressure regulating device based on the sum of the desired alternative braking signal and a detected braking expectation signal. Therefore, after reaching the desired alternative braking pressure based on the desired alternative braking signal, the desired alternative braking signal is reduced, which simultaneously leads to a decrease in the alternative braking pressure. To maintain a constant vehicle deceleration, this reduction must be compensated for by manipulating the braking control device and thus generating a corresponding braking expectation signal. Therefore, a transition process is provided in which the desired alternative braking signal decreases progressively, for example, linearly.

[0024] According to some embodiments of the braking system, the sensor used to detect the desired braking signal can be a control sensor, which is configured to detect the operation of the braking control device, particularly the adjustment stroke. Detection of the adjustment stroke of, for example, the pedal or brake lever, is advantageously relatively fail-safe. Furthermore, the control signal detected by the control sensor can be easily converted and stored, which facilitates the generation of alternative desired braking signals.

[0025] Features and advantages disclosed herein with respect to one aspect of the invention are also disclosed with respect to other aspects of the invention, and vice versa. Attached Figure Description

[0026] The invention is illustrated below with reference to the accompanying drawings. Wherein:

[0027] Figure 1A , Figure 1B A schematic diagram of the hydraulic circuit of a braking system according to an embodiment of the present invention is shown;

[0028] Figure 2 A schematic diagram of a flowchart of a method according to an embodiment of the present invention is shown;

[0029] Figure 3 A qualitative variation graph of braking pressure, brake pedal travel, and braking expectation is shown during a method according to an embodiment of the invention; and

[0030] Figure 4 A graph showing the qualitative changes in braking pressure, brake pedal travel, and braking expectation during a method according to another embodiment of the invention is shown. Detailed Implementation

[0031] Unless otherwise indicated, the same reference numerals in the figures denote the same or functionally identical parts.

[0032] exist Figure 1A and Figure 1B The diagram schematically illustrates a braking system 100 for use in vehicles, particularly road vehicles such as cars, buses, or trucks. The braking system 100 includes at least one wheel brake cylinder 1, a braking force generating assembly 110, a brake pressure regulating device 120, and a control system 130. Figure 1A The image shows the braking force generating assembly 110, in Figure 1B The image shows a brake pressure regulating device 120. The components of the control system 130 are not only present in... Figure 1A Moreover, it also exists in Figure 1B middle.

[0033] As in Figure 1BAs exemplarily shown, each wheel can be provided with a wheel brake cylinder 1. The wheel brake cylinder 1 is configured to convert hydraulic pressure into the movement of a friction pad, so as to press the friction pad against a friction member 101 coupled to the wheel by means of a clamping force proportional to the hydraulic pressure, thereby generating a frictional force or braking force that prevents the wheel from rotating.

[0034] As in Figure 1A As shown, the braking force generating assembly 110 includes an operating sensor 30 and a first pressure generating device 10. Optionally, the braking force generating assembly 110 may further include a master brake cylinder 12 kinematically coupled to the brake pedal 2 and a container 15 for containing brake fluid. As an alternative to the brake pedal 2, a brake lever or a general brake operating device may also be provided. For clarity, the following refers to the brake pedal 2, but the invention is not limited thereto.

[0035] The control sensor 30 is used to detect braking expectation, which represents the target deceleration of the vehicle. For example, the control sensor 30 can be an adjustment travel sensor, which is configured to detect the adjustment travel or movement of the brake pedal 2 that can be operated by the driver.

[0036] The master brake cylinder 12 is kinematically coupled to and operable via the brake pedal 2. Movement of the brake pedal 2 delivers brake fluid from the master brake cylinder 12. Figure 1A As exemplarily illustrated, the master brake cylinder 12 can be hydraulically coupled to a reset simulator 14, which generates a reset force proportional to the actuation stroke of the pedal 2. Furthermore, the master brake cylinder 12 can be hydraulically coupled to and disengaged from the wheel brake cylinder 1 via a first release valve 13A. Figure 1A The illustration exemplarily shows the state in which the first disconnect valve 13A is open and the master brake cylinder 12 is therefore hydraulically coupled to the wheel brake cylinder 1. The first disconnect valve 13A can be, for example, a switchable solenoid valve that is open when there is no current.

[0037] As in Figure 1A As exemplarily illustrated, the first pressure generating device 10 can be implemented, for example, as a plunger 11 having a piston 11B movable by a motor, particularly an electric motor 11A. The first pressure generating device 10 is hydraulically connected to the wheel brake cylinder 1. Figure 1A , Figure 1B As exemplarily illustrated, the first pressure generating device 10 is particularly capable of being hydraulically coupled to and disengaged from the wheel brake cylinder 1 via the second release valve 13B. Figure 1AThe example shows the second separation valve 13B closed and the first pressure generating device 10 thus hydraulically disengaged from the wheel brake cylinder 1. The second separation valve 13B can be, for example, a switchable solenoid valve that is closed when there is no current.

[0038] Brake pressure regulating device 120 is generally used to set wheel-specific (radial-divided) brake pressure, for example, to implement anti-lock braking functions such as ABS or ESP. (As in...) Figure 1B As schematically shown, the brake pressure regulating device 120 includes a second pressure generating device 20, which can be operated independently of the first pressure generating device 10. (As illustrated in...) Figure 1B As exemplarily illustrated, the second pressure generating device 20 can, for example, have one pump 21 for every two wheels or wheel brake cylinders 1, wherein the pumps 21 are operated by a common motor 22, such as an electric motor. However, it is also conceivable that each wheel or each wheel brake cylinder 1 is provided with its own pump 21. Figure 1B As schematically shown, pump 21 is arranged in a hydraulic path that connects the first pressure generating device 10 and the master brake cylinder 12 to the corresponding wheel brake cylinders 1 when the first release valve 13A is open. Furthermore, as in... Figure 1B As schematically and purely exemplary, the brake pressure regulating device 120 can have an inlet valve 23 and an outlet valve 24 for each wheel brake cylinder 1, wherein the inlet valve 23 is arranged in a hydraulic path that connects the pressure output end of the pump 21 to the wheel brake cylinder 1, and wherein the inlet valve 23 is arranged in a hydraulic path that connects the suction input end of the pump 21 to the wheel brake cylinder 1. The inlet valves and outlet valves 23, 24 can in particular be switchable solenoid valves, thereby enabling individualized brake pressure settings for each wheel by operating the second pressure generating device 20 and manipulating the inlet valves and outlet valves 23, 24.

[0039] The control system 130 may specifically have a first control unit 131 and a second control unit 132. However, it is also conceivable in principle to have only one control unit. The control unit 130 may specifically have a processor unit (not shown), for example with one or more CPUs, FPGAs, ASICs, or the like; and a data memory (not shown), particularly non-volatile data memory, such as HDD memory or SSD memory. Software that can be executed by the corresponding processor unit to generate output signals may be stored in the data memory, for example.

[0040] The first control unit and the second control units 131 and 132 are signal-connected, for example, via a data bus 133 (e.g., a CAN bus). Furthermore, the control sensor 30 is connected to the first control unit and / or the second control units 131 and 132, for example, via a data bus 133 or other wireless or wired connections. Additionally, the first pressure generating device 10 is signal-connected to the second pressure generating device 20, and, if necessary, to the inlet valve and outlet valve 23 and 24. This signal connection can also be achieved, for example, via a data bus 133 or other wired or wireless connections. The second control unit 132 is signal-connected to the first pressure generating device 10 and to the first and second separation valves 13A and 13B, for example, via a data bus 133 or other wired or wireless connections. Therefore, the control system 130 is signal-connected to the control sensor 30, the first pressure generating device 10, and the brake pressure regulating device 120. Optionally, the control system 130 can also be signal-connected to the motor 150, for example, via a data bus 133 or other wired or wireless connections. The motor 150 is kinematically coupled to one or more wheels of the vehicle and can operate not only as a motor but also as a generator. The first control unit and / or the second control unit 131, 132 may, for example, have an interface for connecting to the motor 150.

[0041] exist Figure 2 The diagram schematically illustrates the process of a method M for braking a vehicle. This method M can be executed, in particular, by means of the braking system 100 described above. Specifically, the control system 130 can be configured to cause the braking system 100 to implement method M. Therefore, reference is made below to... Figure 1A and Figure 1B The method M is illustrated by the braking system 100 shown in the figure.

[0042] In the first step M1 of the method, a braking expectation signal representing the target deceleration of the vehicle is detected. The braking expectation signal can be detected, for example, based on the operation of the brake pedal 2 or generally based on the operation of the brake control device, for example by means of the adjustment stroke sensor 30.

[0043] In another step M21, braking pressure is generated in the wheel brake cylinder 1 by means of the first pressure generating device 10 based on the detected braking expectation signal. For example, the second control unit 132 can determine the braking pressure from the detected braking expectation signal, and the braking pressure must be set in the wheel brake cylinder to achieve the desired deceleration; and can output a corresponding control signal to the first pressure generating device 10 to cause the first pressure generating device to set the braking pressure. As an alternative or additional solution to step M21, in step M22, braking torque is generated by means of the motor 150, which is kinematically coupled to the vehicle's wheels, based on the braking expectation signal. In particular, in the case of an electric drive vehicle or a hybrid vehicle, the motor 150 driving the wheels can operate as a generator to brake the vehicle. It should be noted that, for example, if the braking torque generated by the motor 150 is insufficient to achieve the desired deceleration of the vehicle, even if pure regenerative braking is performed only by means of the motor 150, the braking force generating component 110 and the braking pressure regulating device 120 are prepared.

[0044] In step M3, a fault condition of the first pressure generating device 10 is detected. For example, the functional state of the first pressure generating device 10 can be determined in step M30. In another step M31, it can be determined whether the functional state corresponds to a fault condition. If the first pressure generating device can no longer set the desired braking pressure, a fault condition of the first pressure generating device 10 may exist. This could be, for example, the following situations: the pressure generating device 10 itself malfunctions, for example, due to a failure of the electric motor 11, or the pressure generating device 10 no longer receives an operating signal from the second control unit 132. The last situation could occur, for example, in the following situations: the detection of the desired braking signal ceases to operate, for example, due to a failure of the sensor 30, or the determination of the braking pressure by means of the second control unit 132 ceases to operate. The detection of the fault condition can be achieved, for example, by means of the first control unit 131 by evaluating the control signal sent to the first control unit 131. The second control unit 132 can, for example, send a first control signal to the first control unit 131. The first control signal may include, for example, the braking pressure, the desired braking signal, and / or a status signal representing the functional state obtained by the second control unit 132. Therefore, the first control unit 131 may detect the fault state of the first pressure generating device 10 based on the functional state included in the control signal, the absence of the control signal from the second control unit 132, or a characteristic parameter in the control signal, such as a gradient.

[0045] As in Figure 2The symbol "-" indicates that if a fault condition is determined to be absent in step M31, the method can, for example, return to step M30. (As shown in...) Figure 2 As indicated by the symbol "+", if a fault condition is determined in step M31, the method proceeds to step M4 and optionally to M40. In the optional step M40, the first separation valve 13A is opened, for example, via the second control unit 132, and further, the second separation valve 13B is optionally closed, for example, via the second control unit 132. Therefore, if a fault condition of the first pressure generating device is detected, the master brake cylinder 12 is hydraulically coupled to the wheel brake cylinder 1, and the first pressure generating device 10 is hydraulically disengaged from the wheel brake cylinder 1.

[0046] In step M4, an alternative braking expectation signal is obtained based on the target deceleration known at a predetermined time point before the fault condition is detected. This can be achieved, for example, by means of a first control unit 131. This first control unit can, for example, determine the adjustment stroke of the brake pedal 2 at a predetermined time point before the fault condition is detected. This can be achieved, for example, by the first control unit 131 obtaining the signal from the control sensor 30 directly from the control sensor 30 or from the second control unit 132, and temporarily storing these values ​​for a certain period of time. These values ​​are always stored, for example, within 500 ms elapsed from the current time point. The last valid value can then be used to determine the braking pressure that should be set in the wheel brake cylinder 1 by the adjustment stroke. Alternatively or additionally, the determination of the alternative braking expectation signal can include determining the braking pressure in the wheel brake cylinder 1 at a predetermined time point before the fault condition is detected. The first control unit 131 can, for example, be connected to a pressure sensor 31, which detects the pressure in the hydraulic path connecting the first pressure generating device 10 to the wheel brake cylinder 1, particularly the pressure upstream of the suction input of the pump 21 of the second pressure generating device 20. Figure 1BAs exemplarily illustrated. In this case, the first control unit 131 can also temporarily store the value recorded by the pressure sensor 31 for a certain period of time, for example, storing the value within 500 ms elapsed from the current time point. The final valid value can then be used as the target pressure that should be set in the wheel brake cylinder 1. The final valid value can be, for example, a value after a predetermined period of time, such as 200 ms. As described above, if the motor 150 is operated as a generator in addition to the braking system 100 to brake the vehicle, an alternative or additional braking torque can also be obtained based on the braking torque generated by the motor 150. The first control unit 131 can, for example, connect to the power electronics of the motor 150 and obtain the braking torque generated by the motor 150 from the power electronics. Then, the final valid braking expectation can be calculated from the braking torque, and the necessary hydraulic braking pressure can be obtained therefrom. If only the braking torque is generated by the motor 150 in step M22, the alternative braking torque is obtained based on the braking torque generated by the motor 150. In this case, the determination of the alternative braking expectation signal may optionally additionally include, for example, determining the braking pressure in the wheel brake cylinder 1 at a predetermined time point before the fault condition is detected, using pressure sensor 31, as described above. Generally, the alternative braking expectation signal can be determined as a constant value corresponding to the last valid braking expectation signal.

[0047] Then, in step M5, the second pressure generating device 20 of the brake pressure regulating device 120 generates the alternative braking pressure in the wheel brake cylinder 1 based on the obtained alternative braking expectation signal. For this purpose, the first control unit 131 outputs an operating signal to the second pressure generating device 20 to cause it to set the obtained alternative braking pressure. Furthermore, the first control unit 131 opens the inlet valve 23 and closes the outlet valve 24 of the corresponding wheel brake cylinder 1. The generation of the alternative braking pressure M5 can, for example, include generating a linear, stepwise, and / or gradually increasing or gradually decreasing pressure rise in the wheel brake cylinder 1. If necessary, the generation of braking torque can be stopped in step M5 by means of the motor 150. Optionally, in step M5, the alternative braking expectation signal can be generated within a predetermined first time period based on the obtained alternative braking expectation signal. The alternative braking expectation signal can be particularly constant during the first time period. After the first time period, the alternative braking expectation signal can decrease to zero, for example, linearly, during a transition period. During the transition period, alternative braking pressure is generated by means of a braking pressure regulating device based on the sum of the alternative braking expectation signal and the detected braking expectation signal.

[0048] The advantage of the described method M is that, once a failure of the first pressure generating device is known, the alternative braking expectation is determined based on the input parameters already obtained before the failure. Therefore, it is not necessary to wait for the driver to operate the brake pedal again to generate a new valid input value, which would be necessary, for example, in cases where a drop in brake pressure occurs in the wheel brake cylinder 1 due to the opening of the first release valve 13A. Based on the alternative braking expectation, the target braking pressure (which at least approximately corresponds to the last valid target braking pressure) can be determined very quickly by means of the control system 130 and immediately set by the brake pressure regulating device.

[0049] exist Figure 3 and Figure 4 In this context, the advantages of method M, along with other advantages, become readily apparent. Figure 3 Four graphs (A), (B), (C), and (D) are shown, where the horizontal axis represents the time axis common to all graphs (A)-(D). The vertical axis of graph (A) plots the current braking pressure in wheel brake cylinder 1. The vertical axis of graph (B) plots the current desired braking signal or the current alternative desired braking signal. The vertical axis of graph (C) plots the adjustment travel of brake pedal 2. The vertical axis of graph (D) plots... Figure 3 The graphs (A)-(D) shown illustrate the braking process performed by the braking system 100 described above according to the method M described above, wherein the deceleration of the vehicle is achieved entirely or at least partially by the braking system 100.

[0050] exist Figure 3 The time point t0 indicated is used to generate braking pressure by means of the first pressure generating device 10 in the manner described above. That is, steps M1, M21, and M3 are implemented. As in Figure 3 As can be seen in the curve (C), pedal 2 maintains a constant adjustment travel. Correspondingly, in Figure 3 The braking expectation shown in graph (B) and in Figure 3 The reaction force at pedal 2, as shown in graph (D), is constant. Correspondingly, as in... Figure 3 As shown in the graph (A), the first pressure generating device 10 generates a constant braking pressure in the wheel brake cylinder 1.

[0051] At time t1, during step M3, a malfunction of the first pressure generating device 10 is detected. Therefore, as described above, the first separation valve 13A opens and the second separation valve 13B preferably closes. Figure 3The graph (A) shows, with a solid line, the further variation curve of the braking pressure generated by the braking pressure regulating device 120 through the implementation method M. Figure 3 The dashed line shown in graph (A) illustrates the braking pressure generated by the brake pressure regulating device 120 when it is operated solely based on the brake expectation signal and without any alternative brake expectation signal. Figure 3 As can be seen in the curve (A), the brake pressure suddenly drops at time t1 because the brake fluid with higher pressure flows into the master brake cylinder 12 due to the opening of the first release valve 13A. Correspondingly, the pedal 2 is pushed back ( Figure 3 The curve (C) shows that the reaction force at pedal 2 increases. Figure 3 The curve (D)). As in Figure 3 As can be seen in graph (B), the braking expectation decreases due to the change in pedal adjustment travel 2. Alternatively, it can be configured so that, in the event of a detected fault in the braking force generating assembly 110, or the first pressure generating device 10, for example, due to a malfunction of the operating sensor 30, a braking expectation signal is initially generated based on the pressure detected by the pressure sensor 31. In this case, the braking expectation also decreases at time t1 because the braking pressure decreases due to the opening of the first release valve 13A. In graph (B), the dashed line shows the braking expectation generated solely by operating the brake pedal 2, corresponding to the braking expectation signal. Figure 3 The dashed line in the graph (B) shows the alternative braking expectation signal, which is generated in step M4 of the method M explained above.

[0052] As in Figure 3 As can be seen from the dashed line in graph (B), the desired alternative braking signal is generated from time point t2 (step M4 of method M). The delay at time point t1 is due, for example, to the evaluation or calculation time required by the control system 130, especially the first control unit 131, to obtain the desired alternative braking signal. Figure 3 As can be seen in the curve (B), an alternative braking expectation signal is generated in such a way that it corresponds to the last valid braking expectation signal before time point t1. The second pressure generating device 20 of the brake pressure regulating device 120 begins to regenerate braking pressure in the wheel brake cylinder 1 based on the alternative braking expectation signal, wherein, as in Figure 3As can be seen from the solid line change curve in graph (A), at time point t4, the braking pressure present in wheel brake cylinder 1 before the failure of the first pressure generating device is reached again. Therefore, the time period t24 between time points t2 and t4 can be called the reaction time of the brake pressure regulating device 120. Figure 3 As can be seen from the dashed line in graph (A), without the described method M, the pressure will decrease further until at time t3, a balance is reached between the reaction force and the braking pressure at brake pedal 2. After this, the driver needs a certain reaction time to further depress pedal 2, as if... Figure 3 As can be seen in the graphs (C) and (D), this process begins again from time point t5. Therefore, the time interval t25 between time points t2 and t5 can be considered as the driver's reaction time.

[0053] In graphs (A)-(C), the dashed lines respectively show the variation curves that would occur without the previously described method M, considering only the operation of pedal 2 to generate the desired braking signal. Figure 3 As can be seen from the dashed line changes in the graphs (C) and (D), starting from time point t5, the adjustment travel of pedal 2 increases again due to the increase in pedal force. For example, in... Figure 3 As can be seen from the dashed line in the curve (B), the desired braking signal is obtained accordingly and the desired braking increases, thereby prompting the brake pressure regulating device 120 to set the brake pressure accordingly, wherein the brake pressure that existed before the failure of the first pressure generating device 10 is reached at time t6 (in Figure 3 (The dashed line in graph (A)). Therefore, time period t46 represents the reduction in the time required to restore the braking pressure that existed before the failure of the first pressure generating device 10, which can be achieved by the method M described above.

[0054] As in Figure 3 As exemplarily shown in the graphs (B)-(D), a transition process can be performed from time point t5 when implementing method M. As already explained, the actual desired braking signal obtained based on the operation of brake pedal 2 can be ignored during the implementation of step M5, at least for a predetermined time period (which is within...). Figure 3 Within the time period t25, only the obtained alternative braking expectation signal is considered to generate the braking pressure in wheel brake cylinder 1. Figure 3 In the graph (B), the double-dotted line represents the braking expectation, which, in the described method M, is generated by actuating the brake pedal 2 after a failure of the first pressure generating device 10, wherein the corresponding adjustment stroke of the pedal 2 and the associated pedal force are determined by... Figure 3The curves are shown as solid lines in graphs (C) and (D). Figure 3 The dashed line in graph (B) illustrates the desired alternative braking signal. Figure 3 The solid line in graph (B) represents the sum of the alternative braking expectation signal and the braking expectation signal generated by manipulating brake pedal 2. (As shown in...) Figure 3 As can be seen in the curves (B)-(D), starting from time point t5, the expected alternative braking signal can decrease to zero within a predetermined transition period t57, as shown in... Figure 3 As exemplarily illustrated, this is achieved, for example, by a linear decrease in the alternative braking expectation signal. To keep the sum of the braking expectation signal generated by manipulating brake pedal 2 and the alternative braking expectation signal constant, the driver must compensate for the decrease in the alternative braking expectation signal by manipulating pedal 2. Figure 3 This is illustrated in the example, where, at time point t7, the alternative braking expectation decreases to zero and the braking expectation signal is provided solely through the manipulation of pedal 2. As described above, the alternative braking pressure is thus generated within the transition period t57 based on the sum of the braking expectation signal and the alternative braking expectation signal. The advantage of this approach is that the driver does not need to manipulate pedal 2 so quickly or forcefully to maintain the vehicle's deceleration.

[0055] By Figure 4 The graphs (A)-(D) shown in the figure illustrate the braking process performed by the braking system 100 according to the described method M when braking torque is first obtained solely by the generator-type operation of the motor 150 (step M22 of method M is implemented).

[0056] exist Figure 4 At the designated time point t0, because the motor generates the desired braking torque independently, no braking pressure is generated by means of the first pressure generating device 10. In other words, braking pressure generated by the motor itself is achieved. Figure 2 Method M consists of steps M1, M22, and M3. For example, in... Figure 4 As can be seen in the curve (C), pedal 2 maintains a constant adjustment travel. Correspondingly, in Figure 4 The braking expectation is shown in graph (B) and in Figure 4 The reaction force at pedal 2 shown in the curve (D) is constant.

[0057] During step M3, a malfunction of the first pressure generating device 10 is detected at time t1. In the current situation, this could be, for example, a malfunction of the control sensor 30. Therefore, as described above, the first separation valve 13A opens and the second separation valve 13B preferably closes. Because the first separation valve 13A is open, the pedal 2 is further moved based on the driver's operation of the pedal 2. Figure 4 The curve (C) shows that the pedal force decreases due to the lack of reset force in simulator 14 at this time. Figure 4 The curve (D)). In Figure 4 The graph (A) shows a further curve of the change in braking pressure generated by the braking pressure regulating device 120 through the implementation method M, with solid lines. Figure 4 The dashed line shown in graph (A) illustrates the braking pressure generated by the brake pressure regulating device 120 when it is operated solely based on the brake expectation signal and without any alternative brake expectation signal. Figure 4 As can be seen in graph (A), the braking pressure increases slightly at time t1 because brake fluid flows out of the master brake cylinder 12 due to the opening of the first release valve 13A and the actuation of the pedal 2. Because the actuation sensor 30 malfunctions in the current example, the braking expectation decreases at time t1. Alternatively, it can be configured so that when a fault condition is detected in the braking force generating assembly 110, or in the first pressure generating device 10, a braking expectation signal is first generated based on the pressure detected by the pressure sensor 31. In this case, the braking expectation at time t1 will also be very small because only pressure equalization occurs by opening the first release valve 13A.

[0058] As in Figure 4 As can be seen from the dashed line in graph (B), the expected alternative braking signal is generated from time point t2 (step M4 of method M). The delay at time point t1 is due, for example, to the evaluation or calculation time required by the control system 130, especially the first control unit 131, to obtain the expected alternative braking signal. Figure 4 As can be seen in the graph (B), the alternative braking expectation signal is generated such that it corresponds to the last valid braking expectation signal before time point t1. Based on the alternative braking expectation signal, the second pressure generating device 20 of the brake pressure regulating device 120 begins to build up braking pressure in the wheel brake cylinder 1, wherein, as in Figure 4As can be seen from the change of the solid line in the graph (A), the braking pressure corresponding to the braking torque is reached at time point t4, which is represented by the braking expectation. This braking torque can, for example, correspond to the braking torque generated in advance by motor 150, where the generator-like operation of motor 150 is stopped. Therefore, the time period t24 between time points t2 and t4 can be called the reaction time of the braking pressure regulating device 120. Figure 4 As can be seen from the dashed line in graph (A), without the described method M, the pressure initially remains constant until the driver reacts and continues to press pedal 2, which then repeats from time point t5, as shown in... Figure 4 As can be seen in the curves (C) and (D). Therefore, the time interval t25 between time points t2 and t5 can be regarded as the driver's reaction time.

[0059] In graphs (A)-(C), the dashed lines respectively show the variation curves that would occur without method M, when only considering the operation of pedal 2 to generate the desired braking signal or the pressure detected by pressure sensor 31. Figure 4 As can be seen from the dashed line change curves in graphs (C) and (D), starting from time point t5, the adjustment stroke of pedal 2 increases further due to the increase in pedal force. Correspondingly, the brake flow moves into wheel brake cylinder 1, the pressure detected by pressure sensor 31 increases, and as in Figure 4 As can be seen from the dashed line in graph (B), the actual braking expectation generated by the driver increases, thereby prompting the brake pressure regulating device 120 to set the brake pressure accordingly, wherein the brake pressure that existed before the failure of the first pressure generating device 10 is reached at time t6 (in Figure 3 (The dashed line in graph (A)). Therefore, time period t46 represents the reduction in the time required to restore the braking torque that existed before the failure of the first pressure generating device 10, which can be achieved by the method M described above.

[0060] As in Figure 4 The curves (B)-(D) are illustrated exemplarily and have been previously combined Figure 3 As explained, the transition process can be executed from time point t5 when implementing method M. As already explained, the actual braking expectation signal obtained based on the operation of brake pedal 2 can be ignored during step M5, at least for a predetermined time period (this time period is within...). Figure 4 Within the time period t25, only the obtained alternative braking expectation signal is considered to generate the braking pressure in wheel brake cylinder 1. Figure 4In the graph (B), the double-dotted line shows the braking expectation generated by operating the brake pedal 2 after the first pressure generating device 10 malfunctions in the described method M, wherein the corresponding adjustment stroke of the pedal 2 and the associated pedal force are... Figure 4 The curves are shown as solid lines in graphs (C) and (D). Figure 4 The dotted line in the curve (B) shows the alternative braking expectation signal. Figure 4 The solid line in graph (B) represents the sum of the alternative braking expectation signal and the braking expectation signal generated by manipulating brake pedal 2. (As shown in...) Figure 4 As can be seen in the curves (B)-(D), the alternative braking expected signal can be generated from time point t5 to time point t7, for example, as in Figure 4 As shown, it decreases linearly to zero. Therefore, the time period between t5 and t7 is called the transition time period t57. In order to keep the sum of the braking expectation signal generated by operating the brake pedal 2 and the alternative braking expectation signal constant, the driver must compensate for the decrease in the alternative braking expectation signal by operating the brake pedal 2. Figure 4 In the example shown, the alternative braking expectation is zero at time t7, and the braking expectation signal is generated solely by actuating pedal 2. As described earlier, within the transition period t57, the alternative braking pressure is thus generated based on the sum of the braking expectation signal and the alternative braking expectation signal. The advantage of this approach is that the driver does not need to actuate pedal 2 so quickly or forcefully to maintain vehicle deceleration.

[0061] Although the invention has been illustrated exemplaryly with reference to embodiments, the invention is not limited thereto and can be modified in a variety of ways. In particular, combinations of the preceding embodiments are also conceivable.

Claims

1. A method (M) for braking a vehicle, comprising: Detect (M1) a braking expectation signal, which represents the target deceleration of the vehicle; Based on the detected braking expectation signal, hydraulic braking pressure (M21) is generated in the wheel brake cylinder (1) by means of a first pressure generating device (10), which is hydraulically connected to the wheel brake cylinder (1). Detect (M3) the fault status of the first pressure generating device (10); If a fault condition of the first pressure generating device (10) is detected, an alternative braking expectation signal (M4) is obtained, wherein the alternative braking expectation signal is obtained based on the target deceleration known at a predetermined time point before the fault condition is detected. and Based on the obtained alternative braking expectation signal, the alternative braking pressure in the wheel brake cylinder (1) is generated by means of a brake pressure regulating device (120), which has a second pressure generating device (20) hydraulically coupled to the wheel brake cylinder.

2. The method (M) according to claim 1, wherein, The detection of the desired braking signal (M1) includes detecting the operation of the braking control device (2), and / or the determination of the alternative desired braking signal (M4) includes determining the adjustment stroke of the braking control device (2) at a predetermined time point before the fault condition is detected.

3. The method (M) according to claim 1 or 2, wherein, The determination of the alternative braking expectation signal (M4) includes determining the braking pressure in the wheel brake cylinder at a predetermined time point before the fault condition is detected.

4. The method (M) according to claim 1 or 2, further comprising: Based on the braking expectation signal, a braking torque (M22) is generated by means of a motor (150) that is kinematically coupled to the wheels of the vehicle.

5. The method (M) according to claim 4, wherein, The alternative braking torque is determined based on the braking torque generated by the motor (150).

6. The method (M) according to claim 1 or 2, wherein, The brake pressure regulating device (120) has a first control unit (131) that operates the second pressure generating device (20), and wherein a fault state of the first pressure generating device (10) is detected according to a control signal sent to the first control unit (131).

7. The method (M) according to claim 6, wherein, The first pressure generating device (10) is operated by the second control unit (132) based on the braking expectation signal, wherein the second control unit (132) generates a first control signal and sends it to the first control unit (131).

8. The method (M) according to claim 1 or 2, wherein, The generation of the alternative braking pressure (M5) includes the generation of a linear, stepwise and / or gradually increasing or gradually decreasing pressure rise in the wheel brake cylinder (1).

9. The method (M) according to claim 2, wherein, By manipulating the brake control device (2), hydraulic reset pressure is generated in the reset simulator (14) by means of the master brake cylinder (12), and wherein, if a fault condition of the first pressure generating device is detected, the master brake cylinder (12) is hydraulically coupled to the wheel brake cylinder (1).

10. The method (M) according to claim 9, wherein, The first pressure generating device (10) is hydraulically separated from the wheel brake cylinder (1).

11. A method (M) for braking a vehicle, the method comprising: Detect (M1) a braking expectation signal, which represents the target deceleration of the vehicle; Based on the braking expectation signal, a braking torque (M22) is generated by means of a motor (150) that is kinematically coupled to the wheels of the vehicle; The first pressure generating device (10) hydraulically connected to the wheel brake cylinder (1) is put into a ready state for generating the braking pressure in the wheel brake cylinder (1) based on the braking expectation signal; Detect (M3) the fault status of the first pressure generating device (10); If a fault condition of the first pressure generating device (10) is detected, an alternative braking expectation signal (M4) is obtained, wherein the alternative braking expectation signal is obtained based on the target deceleration known at a predetermined time point before the fault condition is detected and based on the braking torque generated by the motor. and Based on the desired alternative braking signal, an alternative braking pressure is generated (M5) in the wheel brake cylinder (1) by means of a brake pressure regulating device (120), the brake pressure regulating device having a second pressure generating device (20) hydraulically coupled to the wheel brake cylinder.

12. The method (M) according to claim 1 or 11, wherein, The alternative braking pressure is generated during a predetermined first time period (t25) based on the obtained alternative braking expectation signal, and then the alternative braking expectation signal is reduced to zero during a transition time period (t57), wherein the alternative braking pressure is generated by means of the braking pressure regulating device (120) based on the sum of the alternative braking expectation signal and the detected braking expectation signal during the transition time period (t57).

13. The method (M) according to claim 12, wherein, During the transition period (t57), the expected alternative braking signal decreases linearly to zero.

14. A braking system (100) for a vehicle, comprising: Sensor (30) used to detect braking expectation; Wheel brake cylinder (1) used to generate friction at the wheels of a vehicle. A first pressure generating device (10) is hydraulically coupled to the wheel brake cylinder (1) and configured to generate hydraulic pressure in the wheel brake cylinder (1). Brake pressure regulating device (120) having a second pressure generating device (20) hydraulically coupled to the wheel brake cylinder (1) and configured to generate hydraulic pressure in the wheel brake cylinder (1) independently of the first pressure generating device (10); as well as A control system (130) is signal-connected to the manipulation sensor (30), the first pressure generating device (10), and the brake pressure regulating device (120) and configured to cause the braking system (100) to perform the method (M) according to any one of the preceding claims.

15. The braking system (100) according to claim 14, wherein, The sensor used to detect the desired braking signal is a control sensor (30), which is configured to detect the operation of the braking control device (2).

16. The braking system (100) according to claim 15, wherein, The control sensor is configured to detect the adjustment stroke of the brake control device (2).

Images