Brake system for motor vehicle

Abstract

The invention relates to a brake system for a motor vehicle, comprising a hydraulic brake device (10) and an electric brake device (20), which are designed at least partially redundant to one another. In particular, in the event of a failure of the hydraulic component, the braking demand may be electrically assisted.

Description

[0001] This application is a divisional application of the invention patent application with the application date of July 29, 2019, application number 201980052160.1, and invention name “Braking system for a motor vehicle”. Technical Field

[0002] The invention relates to a brake system for a motor vehicle having a plurality of wheels. Background Art

[0003] Motor vehicles are usually equipped with a braking system that acts on the wheels of the motor vehicle. A typical passenger car, for example, has four wheels, all of which can be braked by means of a service brake. In addition, motor vehicles usually also have a parking brake, which prevents the vehicle from rolling when stationary.

[0004] While in earlier motor vehicles, the service brake and the parking brake were usually considered and implemented separately from each other, since these brakes performed different tasks, recent developments have increasingly sought to integrate the two brake systems in order to achieve additional or better functions. However, this also places higher demands on operational safety. Summary of the invention

[0005] It is therefore an object of the present invention to provide a brake system for a motor vehicle which is designed as an alternative to the prior art, for example with greater operational safety.

[0006] The above object is achieved according to the present invention by a brake system as described below.

[0007] The invention relates to a braking system for a motor vehicle having a plurality of wheels. The braking system has a hydraulic braking device, which is designed to act on a first group of wheels. The braking system has an electric braking device, which is designed to act on a second group of wheels. The braking system also has a first control device, which is configured to control the hydraulic braking device. In addition, the braking system has a second control device, which is configured to control the electric braking device. The braking system also has an energy supply device, which is configured to supply electrical energy to the first control device and the second control device separately from each other.

[0008] Here, the number of wheels is plural. In particular, the number of wheels is preferably four, so that the motor vehicle has four wheels.

[0009] An increased failsafety can be achieved by the brake system according to the invention, in particular because the brake device has independent control devices and these control devices can also be supplied with electrical energy independently of one another.

[0010] The first set of wheels can in particular include all wheels. This corresponds to a typical design of a motor vehicle, in which all wheels are braked.

[0011] Usually, the second group only includes a part in the wheel, such as the rear wheel of a motor vehicle. However, the second group may also include other parts in the wheel, such as also may include all wheels.

[0012] The configuration of the energy supply device for supplying energy to the two control devices separately can be realized, for example, by independent lines or other independent components. In particular, the system can be designed to be completely or partially redundant. This significantly increases the fault safety.

[0013] According to a preferred embodiment, the electric brake device is a parking brake. For example, the parking brake can act on the rear wheels of the vehicle. According to a preferred embodiment, the hydraulic brake device is a service brake. For example, the service brake can act on all wheels.

[0014] For example, a parking brake may be specifically designed to hold a vehicle stationary when stationary and to secure the vehicle against unintentional movement. Whereas a service brake is generally used to decelerate a moving vehicle. However, the functions of different brake devices may also be combined.

[0015] For generating pressure, the hydraulic brake device preferably has a brake cylinder actuated by the driver and an electrically actuated actuator. In this way, two possibilities can be combined for generating hydraulic pressure, wherein both direct actuation by the driver and indirect or purely electrically initiated actuation by means of an electrically actuated actuator are possible. In particular, a hydraulic fallback level / failure recovery strategy can be provided, in which the brake cylinder actuated by the driver generates pressure that acts directly on the wheels. This makes it possible to stop the vehicle even if all electrical systems fail.

[0016] The energy supply device preferably has an inverter, a battery and / or a capacitor as a device for extracting and / or storing electrical energy. This is used in particular to ensure input energy for the energy supply, which can then be transmitted to the control device. The inverter can, for example, generate an alternating current, which can, for example, be rectified. For example, an alternator can be used for this purpose. The battery can store electrical energy, for example, in the event of an overload state or failure of the alternator and during periods of parking. The capacitor can be used in particular to smooth out short-term fluctuations.

[0017] The energy supply device is preferably designed to selectively connect the first control device and / or the second control device to one or more devices for extracting and / or storing electrical energy. This ensures that energy is supplied to both control devices in the best possible way. Such devices can be, for example, the components just mentioned above: inverters, alternators, batteries or capacitors.

[0018] The first control device is preferably configured to perform one or more of the following functions:

[0019] - detection and / or processing of a driver's braking request,

[0020] -Communication via CAN bus,

[0021] - Communication with the vehicle network,

[0022] - Process the signals from the wheel speed sensors,

[0023] - supplying hydraulic energy to the hydraulic brake device,

[0024] - calculation and / or execution of brake regulation functions, Anti-lock Braking System (ABS), Electric Brakeforce Distribution (EBD) and / or Electronic Stability Program (ESP),

[0025] -Determining driver demand via a parking brake switch, via a human machine interface and / or via a vehicle network.

[0026] These functions are usually used to control a hydraulic brake system. It should be understood that all possible combinations and sub-combinations of the functions described are possible. Combinations with other functions are also possible.

[0027] The second control device is preferably configured to perform one or more of the following functions:

[0028] - detection and / or processing of a driver's braking request,

[0029] - detection and / or processing of parking status information,

[0030] - Generate a substitute signal for stationary state recognition using information from the vehicle network, from the camera, radar, transmission and / or engine,

[0031] - detection and / or processing of wheel slip information,

[0032] - detection and / or processing of the position of the electric parking brake switch,

[0033] -Supply electrical energy to the electric brake device.

[0034] These are typical functions of a control device for a parking brake. It should be understood that all possible combinations and sub-combinations of the functions described are possible. Combinations with other functions are also possible.

[0035] In particular, the second control device can be configured to detect a vehicle standstill, for example by means of wheel speed sensors or camera signals, and to apply the parking brake in response to an activated parking brake switch when the vehicle standstill has been detected.

[0036] According to a preferred embodiment, which may also constitute an independent aspect of the present invention, the first control device and the second control device are configured to assist the driver's braking demand by means of the hydraulic brake device if the first control device and the hydraulic brake device function without failure, and to assist the driver's braking demand by means of the electric brake device in the event of a complete or partial failure of the first control device and / or the hydraulic brake device.

[0037] In the case of fault-free operation of the service brake or another hydraulic brake device, this allows normal braking in response to a driver braking demand, wherein the driver braking demand can be assisted. For example, the pressure generated by the driver in the brake cylinder can be transmitted to the wheels, and the boost can be performed additionally by a pump, a linear actuator or other electrically operated devices. Alternatively, the driver braking demand can also be detected only electronically and implemented entirely by electrically generating pressure. For this purpose, a simulator is usually used, which generates a certain resistance to the driver.

[0038] However, if the components required for this purpose fail completely or partially, assistance can be provided to the driver's braking request with the aid of the electric brake device. For example, the pressure generated by the driver in the master brake cylinder can be transmitted to the wheels, wherein the electric brake device generates an additional braking torque. This allows significantly higher safety, since assistance is provided in fulfilling the driver's braking request even in the event of a complete or partial failure of the hydraulic brake system or its electrical components.

[0039] The reliability is additionally increased by the embodiment described further above with two independent control devices and separate energy supplies.

[0040] The first control device preferably has one or more of the following components:

[0041] a power control unit (PCU) configured to supply voltage to the internal electronics, read in wheel speed information and / or actuate valves and / or actuate hydraulic regulators and / or actuate actuators,

[0042] An execution unit for software for regulating a hydraulic brake system.

[0043] The second control device preferably has one or more of the following components:

[0044] - a microcontroller configured to supply voltage to the internal electronics and / or read in wheel speed information,

[0045] - an execution unit for software for regulating an electric braking device,

[0046] a parking brake control unit configured to actuate the H-bridge,

[0047] -H-bridge.

[0048] With regard to the above component list, it should be noted that these components can be combined with each other in any combination or sub-combination. Combinations with other elements are also possible.

[0049] The components of the first control device are preferably structurally and / or electrically separated from the components of the second control device. This further increases the reliability, since, for example, a fault state occurring in one control device does not necessarily have to be transmitted to the other control device. For example, the influence of an overvoltage state can thus be limited. For example, separate circuit boards or housings can be used.

[0050] The brake system is preferably configured to output a fault message and / or allow operation of the electric brake device, which occurs in response to the detected failure of the first control device, only for a predetermined period of time or until a predetermined event, in the event of a complete or partial failure of the first control device. Such a predetermined event may be, for example, a vehicle parking state or a repair shop visit. This overcomes the risk that the driver himself, in the event of a complete or partial failure of the hydraulic brake device, relies on additional actions of the electronic brake device and postpones or seeks to avoid repair work. For example, by means of the measures described, the driver can be prompted and prompted to visit a repair shop in order to repair the defective component.

[0051] The electric brake device is preferably designed for direct electric braking of the wheels. This means in particular that no hydraulic intermediate components are provided. In particular, components operated by an electric motor, an electromagnet or some other electrical device can act directly to generate a braking force.

[0052] The brake system is preferably designed for a motor vehicle with four wheels, i.e., two front wheels and two rear wheels, wherein the first group includes all four wheels and wherein the second group includes the rear wheels. This corresponds to the typical configuration of a brake system in a common passenger car. However, it should be pointed out that the brake system according to the invention can also be used without problems in other vehicles with a different number of wheels or with a different division of the first and second groups. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] A person skilled in the art will derive further features and advantages from the exemplary embodiments described below with reference to the accompanying drawings, in which:

[0054] Figure 1 shows the braking system, and

[0055] Figure 2 A circuit diagram showing components of a brake system is shown. DETAILED DESCRIPTION

[0056] Figure 1 A brake system 5 according to an embodiment of the invention is shown in a purely schematic diagram. The brake system 5 has a hydraulic brake device 10 with an associated first control device 12. The brake system 5 has an electric brake device 20 with an associated second control device 22, the first control device 12 being configured to control the hydraulic brake device 10 and supply it with energy. The second control device 22 is configured to control the electric brake device 20 and supply it with energy.

[0057] An energy supply device 30 is provided for the public energy supply. The energy supply device has an inverter in the form of an AC generator 32 , a battery 34 and a capacitor 36 .

[0058] The energy supply device 30 is designed to selectively connect the first control device 12 and the second control device 22 to each of the alternator 32, the battery 34 and the capacitor 36. Therefore, electric energy can be supplied to the two control devices 12, 22, and thus the two brake devices 10, 20 can also be supplied with electric energy separately from each other.

[0059] When all components, in particular the first control device 12 and the components of the hydraulic brake system 10, are operating normally, a driver braking demand is detected, which can be triggered by the driver, in particular by operating the brake pedal. The driver braking demand can then be electrically assisted, for example, by a linear actuator (not shown).

[0060] However, if this required component fails, the second control device 22 can use the electronic brake system 20 to assist the driver's braking demand. Otherwise, the electronic brake system 20 mainly acts as a parking brake.

[0061] Typical vehicles are currently configured at least so that in the event of a vehicle failure, that is to say a failure of the entire vehicle electrical system, the vehicle can perform a 2.44 m / s acceleration with a driver-applied pressure of 500 N. 2 However, typically, it is desired to achieve, for example, 4 m / s in the presence of a braking force of 200 N. 2 or 4.88m / s 2deceleration.

[0062] In order to increase the deceleration and / or reduce the brake pressure applied by the driver required for this purpose, it is usually necessary to electrically detect and boost the brake pressure applied by the driver by means of an energy source.

[0063] In normal operation, when the components are working normally, the driver's braking request and power assistance are usually implemented by means of a hydraulic brake device. However, in the case of the embodiment currently used, if the power assistance fails, then under the condition of a braking force of 500N, only about 2.5m / s can usually be ensured. 2 Up to 4m / s 2 deceleration.

[0064] By means of the embodiments of the brake system described here, redundancy of the driver assistance can be ensured by establishing independence between the generation of the braking torque by means of the hydraulic actuator and the electric actuator (typically the parking brake). This independence is not only realized in the actuator itself, but can also relate, for example, to the following aspects:

[0065] - voltage supply,

[0066] - sensor information (sensor system),

[0067] -evaluate(logical device),

[0068] -Execute (actuator device).

[0069] The embodiment of the brake system 5 described here ensures that, in the case of most known individual faults, the driver's braking request is implemented by hydraulic or electrical boosting. Such boosting can be provided, for example, at the rear axle.

[0070] Figure 1 The components described in the embodiment can communicate with each other, in particular via a vehicle bus, such as a CAN bus. For the sake of simplicity, such a bus system is not shown.

[0071] The first control device 12 and the hydraulic brake device 10 can also be regarded as the first path of the brake system 5, and the second control device 22 and the electric brake device 20 can be regarded as the second path of the brake system 5. Here, the two paths are preferably designed redundantly with respect to each other.

[0072] Here, the first path usually has the following tasks:

[0073] - detect the driver's braking demand,

[0074] - establish communication with the vehicle network,

[0075] - Read wheel speed sensor information,

[0076] - supplying hydraulic energy ("brake pressure") to the brake system,

[0077] - Calculation of the associated brake regulation functions, such as ABS, EBD or ESP (also called AYC).

[0078] The second path usually has the following tasks:

[0079] - detect the driver's braking demand,

[0080] - detect the vehicle state relative to the stationary state,

[0081] - detect vehicle conditions related to wheel slip,

[0082] - Read in the parking brake switch,

[0083] - supplying electrical energy to the parking brake actuator in order to generate a braking torque by means of said parking brake actuator.

[0084] Here, the first path generally refers to the ability of an electronic control unit (ECU) to generate a braking torque via a hydraulic device, and the second path generally refers to the ability of a parking brake actuator to generate a braking torque.

[0085] The boosting of the driver's brake request is achieved in each case via one or both of these paths. As long as the first path is available, the boosting is usually performed with the help of hydraulic means for comfort reasons. In the event of a malfunction or unacceptable degradation, the boosting can be performed by the second path. Combinations are also possible.

[0086] Figure 2 A circuit diagram is shown with a possible redundancy concept with respect to sensors, processing devices and actuators.

[0087] Here, the left side to the X-Bar is used to generate mutually redundant voltages KL30_1 and KL30_2.

[0088] This can be implemented as follows:

[0089] - Independence between KL30_1 and KL30_2 is ensured by clear separation of input voltages,

[0090] - Switching capability of the X-Bar for switching the input voltage to KL30_1 and / or KL30_2 depending on the status.

[0091] In this example, the execution path consists of the following modules:

[0092] First path ("Hydraulic"):

[0093] -PCU 1:

[0094] - voltage supply to internal electronics,

[0095] - Read wheel speed information,

[0096] - control of valves (“valve”) and hydraulic regulators (“LAC”),

[0097] -MCU 1:

[0098] - Execution unit for the software of the hydraulic brake control system (CPU).

[0099] Second path ("Parking brake"):

[0100] -PCU 2:

[0101] - as voltage supply to internal electronics,

[0102] - Read the rear wheel speed information,

[0103] -MCU 2:

[0104] - an execution unit for the software of the parking brake control device (CPU),

[0105] -Parking brake actuator:

[0106] - actuating the H-bridge to operate the parking brake actuator,

[0107] -H-bridge:

[0108] -Control the current based on the drive control commands from IPEX.

[0109] Alternatively, components may be combined in different ways in each path, as long as the independence of these components from components in other paths is ensured.

[0110] Below, the functionality of the system shown will be described, which can ensure redundancy, for example:

[0111] 1. In the absence of a fault, wheel slip is determined directly in the first path via wheel speed information. If this communication path fails, the rear wheel speed signal is switched to the second path via a switch in the control unit (MUX). With this switch, the second path can autonomously adjust for wheel slip.

[0112] 2. If the power source itself fails, driver assistance operation is possible via the first path. The brake force distribution can be set via a static EBD with a fixed characteristic curve so that driver assistance can be achieved safely without premature slip at the rear axle (correct locking sequence).

[0113] 3. The signal of the wheel speed sensor or the signal of the driver's request is transmitted via the internal bus to the second path, so that the parking brake software located there allows the parking brake to be statically triggered or set only in the safe state.

[0114] 4. In the control unit, there are two independent sensors (usually a pressure sensor and a position sensor) for determining the driver's braking request. Usually, both sensors are connected to the first hydraulic path in order to be able to react quickly to the driver's request. In the event of a fault, one of the sensors is directed to the second path via a switching mechanism. This can be used to read in and evaluate the driver's request and to adjust the braking torque via the electric parking brake actuator.

[0115] 5. The system will use monitoring devices to check the function of the valves, hydraulic regulators and parking brake actuators. If redundancy loss occurs here, the driver must be warned. In addition, assistance for braking requirements is ensured via another path.

[0116] 6. If the driver is already performing a hydraulic braking operation and if a loss of boosting capacity is detected by existing pressure and / or volume monitoring, the driver is informed and the second path is activated.

[0117] 7. In order to ensure that the system is awakened by the parking brake switch, the second path is provided with a facility to wake up the first path via a wake-up line.

[0118] 8. If the ability to identify the stationary state through the wheel speed sensor has been lost, both the first path and the second path can determine the stationary information from other sensors of the vehicle through CAN communication. Other sensors can be, for example, cameras, radars or transmissions.

[0119] The components and processes mentioned are merely exemplary. They can be implemented exactly as described above, or individually or in any combination.

[0120] The electric boost of the brake request can be set in particular so that the deceleration desired by the driver is achieved. At the beginning of the braking process triggered by the driver, pure hydraulic braking without boost usually takes place. Starting from a certain value, the electric parking brake is adjusted so that a specified braking torque is generated and the vehicle is thus additionally decelerated.

[0121] After a certain time interval, for example after an ignition switch, the electric assistance can be stopped or reduced. It makes sense if assistance with the electric parking brake does not lead to a loss of comfort so that the driver or owner of the vehicle starts repairs, because they are also satisfied with the degraded behavior. In the case of long-term operation, this would lead to safety risks and increased wear. The driver should therefore be motivated to repair the damaged parts.

[0122] The inclusion of a claim in this application does not constitute a disclaimer of further protection.

[0123] If it turns out that a feature or a group of features is not absolutely necessary during the process, the applicant has now committed himself to formulating at least one independent claim which no longer has this feature or this group of features. This can, for example, involve a subcombination of the claims filed on the filing date or a subcombination of the claims filed on the filing date which is limited by other features. Such a claim or feature combination to be restated is to be understood as being included in the disclosure content of the present application.

[0124] In addition, it should be noted that the improvements, features and variants of the present invention described in different embodiments or exemplary embodiments and / or shown in the accompanying drawings can be combined with each other in any way. Single or multiple features can be interchanged with each other at will. The resulting feature combination can be understood to be included in the disclosure of the present application.

[0125] References in dependent claims should not be understood as a waiver of independent, specific protection for the features of the dependent claims referred to. These features can also be combined with other features as desired.

[0126] Features disclosed only in the description or only in the description or in the claims in combination with other features may in principle be independent features important to the invention. Therefore, they may also be individually admitted to the claims to distinguish the prior art.

Claims

1. A braking system (5) for a motor vehicle having a plurality of wheels, wherein: The braking system (5) comprises the following components: - a hydraulic braking device (10) designed to act on a first group of wheels, - an electric braking device (20) designed to act on a second set of wheels, - a first control device (12) configured to control the hydraulic brake device (10), - a second control device (22) configured to control the electric brake device (20), and - an energy supply device (30) configured to supply electrical energy to the first control device (12) and the second control device (22) independently of each other, wherein the first control device (12) is configured to detect and / or process a driver's braking demand, and The second control device (22) is configured to detect and / or process a driver's braking request.

2. The brake system (5) according to claim 1, wherein: The electric brake device (20) is a parking brake; and / or The hydraulic brake device (10) is a service brake.

3. The braking system (5) according to claim 1 or 2, wherein: The hydraulic brake device (10) has a driver-actuated brake cylinder and an electrically-actuated actuator for generating pressure.

4. The brake system (5) according to any one of the preceding claims, wherein: The braking system comprises two independent sensors for determining the driver's braking request, in particular a pressure sensor and a position sensor.

5. The brake system (5) according to claim 4, wherein: Both sensors are connected to the first hydraulic path; In the event of a fault, one of the two sensors is directed to the second path via the switching mechanism.

6. The brake system (5) according to any one of claims 1 to 4, wherein: The driver's braking request is only detected electronically and implemented entirely by electrically generating pressure.

7. The brake system (5) according to any one of the preceding claims, wherein: The second path is provided with a facility to wake up the first path via a wake-up line.

8. The brake system (5) according to any one of the preceding claims, wherein: The energy supply device (30) has an inverter (32), a battery (34) and / or a capacitor (36) as devices for extracting and / or storing electrical energy.

9. The brake system (5) according to any one of the preceding claims, wherein: The energy supply device (30) is designed to selectively connect the first control device (12) and / or the second control device (22) to one or more devices for extracting and / or storing electrical energy.

10. The brake system (5) according to any one of the preceding claims, wherein: The first control device (12) is configured to perform one or more of the following functions: -Communication via CAN bus, - Communication with the vehicle network, - Process the signals from the wheel speed sensors, - supplying hydraulic energy to the hydraulic brake device (10), - calculation and / or execution of brake regulation functions, Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD) and / or Electronic Stability Program (ESP), -Determining driver demand via a parking brake switch, via a human machine interface and / or via a vehicle network.

11. The brake system (5) according to any one of the preceding claims, wherein: The second control device (22) is configured to perform one or more of the following functions: - detection and / or processing of stationary information, - Generate a substitute signal for standstill detection using information from the vehicle network, from cameras, radar, transmission and / or engine, - detection and / or processing of wheel slip information, - detection and / or processing of the electric parking brake switch position, - Supplying electrical energy to the electric brake device (20).

12. The brake system (5) according to any one of the preceding claims, wherein: The first control device (12) and the second control device (22) are configured to: if the first control device (12) and the hydraulic brake device (10) function without failure, assist the driver's braking demand through the hydraulic brake device (10); and in the event that the first control device (12) and / or the hydraulic brake device (10) completely or partially fail, assist the driver's braking demand through the electric brake device (20).

13. The brake system (5) according to any one of the preceding claims, wherein: The first control device (12) has one or more of the following components: a power control unit (PCU) configured to supply voltage to the internal electronics, to read in wheel speed information and / or to actuate valves and / or to actuate hydraulic regulators and / or to actuate actuators, - an execution unit for software for regulating the hydraulic brake device (10).

14. The brake system (5) according to any one of the preceding claims, wherein: The second control device (22) has one or more of the following components: a microcontroller configured to supply voltage to the internal electronics and / or to read in wheel speed information, - an execution unit for software for regulating the electric brake device (20), a parking brake control unit configured to actuate the H-bridge, -H-bridge.

15. The brake system (5) according to any one of the preceding claims, wherein: The electric brake device (20) is designed for direct electric braking of wheels.

16. Braking system (5) according to any one of the preceding claims, wherein: The brake system (5) is designed for a motor vehicle having four wheels, namely two front wheels and two rear wheels. The first set includes all four wheels, and The second group includes the rear wheels.

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