Method for operating a brake system of a motor vehicle, brake system

Abstract

The invention relates to a method for operating a motor vehicle (1), the motor vehicle having at least one prime mover (2) with an engine control unit (3) and a brake system (5), wherein the brake system (5) has at least one wheel brake (6) and at least one electromechanical brake booster (7) with a booster control unit (9), and a driving stability control unit (10), which is designed to influence the brake system (5) in order to stabilize the driving state of the motor vehicle (1), wherein at least one of the control units is activated when the brake system (5) is activated and the brake system (5) is monitored with respect to the occurrence of a fault message. Provision is made for monitoring the engine control unit (3) to begin only after a vehicle movement of the motor vehicle (1) has been detected.

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle having at least one prime mover with an engine control device and a braking system, wherein the braking system has at least one wheel brake and at least one electromechanical brake booster with a booster control device, and a driving stability control device, which is designed to influence the braking system in order to stabilize the driving state of the motor vehicle, wherein when the braking system is activated, at least one of the control devices is activated and the braking system is monitored with respect to the occurrence of fault messages.

[0002] The present invention further relates to a brake system which is designed to carry out the above-described method. Background Art

[0003] Braking systems and methods for operating such systems are known from the prior art. Control units are assigned to essential components of a motor vehicle. Thus, an electromechanical brake booster can be operated via a booster control unit. A driving stability control unit is used to intervene in the braking system to restore or ensure the vehicle's driving stability, particularly in emergency situations. Such booster control units are known, for example, as ESP (Electronic Stability Program) control units. The booster control unit is connected to, for example, multiple wheel brakes to actuate or influence them individually, regardless of the braking request, to prevent the vehicle from rolling away, spinning, or seizing. The booster control unit, for example, controls the brake booster based on the braking request to adjust the hydraulic pressure required in the braking system to implement the braking request. Furthermore, it is known to assign an engine control unit to the motor vehicle's prime mover, which controls and monitors the prime mover, particularly in the form of an internal combustion engine. To this end, the control units communicate with each other via a fault message monitoring communication network, for example, with fault messages being transmitted from one control unit to the other. When the brake system is activated, the amplifier control unit and the driving stability control unit are currently activated simultaneously, so that both control units are initialized simultaneously and their respective software monitoring begins. However, because the engine control unit is typically only activated when the vehicle's ignition system is activated, it remains deactivated at this point in time. This results in, for example, the amplifier control unit not receiving any signals from the engine control unit, and thus generating a fault message that is, for example, entered into a fault memory and / or notified to the vehicle occupants acoustically or visually. Summary of the Invention

[0004] The method according to the invention, having the features of claim 1, has the advantage that the braking system can be activated without generating a fault message from the engine control unit, thus avoiding false alarms. To this end, the invention provides that monitoring of the engine control unit begins only after the vehicle's movement is detected. Thus, the invention provides that monitoring of the engine control unit begins only when the vehicle is in motion, in particular when driven by a prime mover. This ensures that the engine control unit is only checked when the vehicle's ignition system is activated, and that its messages can be detected by one of the other control units. This ensures that, of the three control units mentioned, only the driving stability control unit and the booster control unit are initialized and tested simultaneously when the braking system is activated, thus eliminating engine control unit fault messages.

[0005] As already mentioned above, when the brake system is activated, the amplifier control unit and the driving stability control unit are preferably monitored. Thus, when activated, the two control units directly assigned to the brake system are initialized and monitored and tested for their functional capabilities.

[0006] Furthermore, it is preferably provided that the vehicle motion of the motor vehicle is determined based on the vehicle's speed and / or acceleration. This ensures that the vehicle's ignition system has been activated and the engine control unit can be included in the monitoring, without generating a fault message because the engine control unit has not yet been activated. The vehicle's speed and / or acceleration are preferably determined by a driving stability control unit having one or more acceleration sensors and / or one or more speed sensors or rotational speed sensors, or having access to such sensors located in or on the vehicle.

[0007] Furthermore, it is preferably provided that signals from the vehicle stability control system and / or the engine control system are detected to determine the vehicle motion of the motor vehicle. The vehicle stability control system, in particular, provides the aforementioned signals relating to the vehicle's speed and / or acceleration. The engine control system provides, for example, driving signals that relate to a specific driving operation or a target speed or acceleration. These driving signals can be used, for example, to perform plausibility checks on the signals or data provided by the vehicle stability control system.

[0008] The activation of the brake system is particularly preferably initiated based on the door position of the motor vehicle. For this purpose, the motor vehicle doors are continuously monitored, for example. If the door is detected to be open or unlocked, the brake system is already activated, so that it is already available when the driver of the motor vehicle sits down in the driver's seat.

[0009] The brake system according to the invention, having the features of claim 6, is characterized in that the booster control unit and / or the driving stability control unit are specifically designed to carry out the method according to the invention. Optionally, a monitoring control unit is provided for monitoring the existing control units, namely the driving stability control unit, the booster control unit, and the engine control unit, for fault functions. The monitoring control unit is particularly designed to monitor the communication network for the occurrence or development of fault messages, and in particular to detect the start of the motor vehicle and activate the control units according to the invention, wherein the control units communicate with each other via the communication network. Further advantages and preferred features, as well as combinations of features, can be derived from the preceding description and from the claims.

[0010] In particular, the driving stability control device has at least one acceleration sensor, speed sensor and / or rotational speed sensor, so that the aforementioned signals / data can be detected.

[0011] The communication network is particularly preferably designed as a bus system via which the control devices communicate with one another.

[0012] Furthermore, it is preferably provided that a device is present for determining the desired activation of the brake system. In particular, the device is connected to the control device or to at least one of the control devices in order to control it accordingly when activation is detected.

[0013] The device is particularly preferably designed as a door lock or door contact. If the door lock is unlocked or the door contact is opened by moving the vehicle door from a closed travel position to its open position, the braking system is activated by the device, as already described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be described in more detail below with reference to the accompanying drawings.

[0015] Figure 1 A simplified diagram of a motor vehicle is shown, and

[0016] Figure 2 A flow chart is shown to illustrate an advantageous method for operating a motor vehicle. DETAILED DESCRIPTION

[0017] Figure 1 A simplified diagram shows a motor vehicle 1 having an internal combustion engine as a prime mover 2, which is operatively connected to at least two wheels of the motor vehicle for driving the same. An engine control unit 3 is assigned to the internal combustion engine, which is controlled by the engine control unit, for example, in response to an operation of an accelerator pedal 4. Furthermore, motor vehicle 1 has a braking system 5 comprising a plurality of wheel brakes 6, each of which is assigned a vehicle brake to one of the wheels of motor vehicle 1, so that each wheel can be braked individually. Braking system 5 also includes an electromechanical brake booster 7, a brake pedal 8, and a booster control unit 9. In response to an operation of brake pedal 8, booster control unit 9 actuates booster 7 to generate a hydraulic pressure in the hydraulically configured braking system 5, which is applied to wheel brakes 6. Each wheel brake 6 has an inlet valve and, preferably, an outlet valve, which can be individually actuated to adjust the brake pressure or braking force on a wheel-by-wheel basis using the hydraulic pressure provided at the respective wheel brake. For this purpose, in particular a driving stability control device 10 is provided which, during operation, continuously monitors the driving state of the motor vehicle and, if necessary, actuates the wheel brakes 6 independently of the braking force requirement achieved in order to reset or ensure the driving stability of the motor vehicle 1 .

[0018] Control devices 3, 9, and 10 are interconnected via a communication network 11 (not shown in greater detail here). Communication network 11 is, for example, a bus system to which the control devices are connected. Control devices 3, 9, and 10 are configured to monitor their own operation or the operation of other components, such as other control devices, for the occurrence of a fault and, upon detecting a fault, output a fault message that is distributed or forwarded via communication network 11.

[0019] Figure 2 A flow chart is shown for illustrating an advantageous method for operating motor vehicle 1 and in particular brake system 5 .

[0020] In step S1 , the method begins, for example, with the detection of an unlocking of a door of motor vehicle 1 .

[0021] In the following step S2, the optionally provided door contact 12 assigned to the driver's door is monitored with respect to whether the driver's door (Fahrertür) is open. If this is not the case (no (n)), refer back to step S1. However, if door contact operation or door opening is detected (yes (j)), a start command is output to the control devices 9 and 10 of the brake system 5 in the following step S3, so that the control devices 9 and 10 are initialized and started. The start of the motor vehicle or at least the expected or possible start of the motor vehicle is thus determined with the aid of the door contact 12. The control devices 9 and 10 are initialized simultaneously and therefore also go through a program routine more or less simultaneously, which is used to monitor the respective control devices and the motor vehicle with respect to fault messages. If a fault message is detected, the fault message is fed into the communication network 11. Then, in step S4, for example, by a superior control device, in particular such as Figure 1 If the fault message is relevant, a warning message is output to the driver of the motor vehicle 1 and / or a component of the motor vehicle to which the fault message is relevant is optionally deactivated or placed in an emergency operating state.

[0022] Furthermore, after control devices 9 and 10 have been activated, motor vehicle 1 is monitored in step S5 with respect to whether an active driving movement has occurred. For this purpose, for example, data from driving stability control device 10 , which has access to data from at least one acceleration sensor and / or speed sensor, is monitored with respect to whether a significant vehicle movement of motor vehicle 1 has occurred, indicating that the ignition system of motor vehicle 1 has been actuated.

[0023] Only if a driving movement is detected or determined (yes (j)) is the engine control unit also included in the monitoring for the fault message in the subsequent step S6. It is assumed that engine control unit 3 is also activated and initialized only when motor vehicle 1 is set in motion, so that the fault message subsequently output by the engine control unit is also relevant and is not based on the fact that engine control unit 3 has not yet been initialized.

[0024] Thus, an advantageous method makes it possible to avoid fault messages due to engine control unit 3 not yet being activated or initialized.

Claims

1. A method for operating a motor vehicle (1), the motor vehicle having at least one prime mover (2) with an engine control device (3) and a brake system (5), wherein the brake system (5) has at least one wheel brake (6) and at least one electromechanical brake booster (7) with a booster control device (9), and a driving stability control device (10) which is designed to influence the brake system (5) in order to stabilize the driving state of the motor vehicle (1), wherein at least one of the control devices is activated when the brake system (5) is activated and the brake system (5) is monitored with respect to the occurrence of a fault message, characterized in that Monitoring of the engine control unit (3) is initiated only after a vehicle movement of the motor vehicle (1) is detected.

2. The method according to claim 1, characterized in that When the brake system (5) is activated, the amplifier control device (9) and the driving stability control device (10) are monitored.

3. The method according to 1 or 2, characterized in that The vehicle movement of the motor vehicle (1) is determined based on the driving speed and / or acceleration of the motor vehicle (1).

4. The method according to 1 or 2, characterized in that In order to determine the vehicle movement of the motor vehicle (1), signals of the driving stability control device (10) and / or the engine control device (3) are detected.

5. The method according to 1 or 2, characterized in that The activation of the brake system (5) is initiated depending on the operating state of the door lock or door contact (12) of the motor vehicle (1).

6. A motor vehicle (1), comprising a prime mover (2), an engine control device (3) being assigned to the prime mover, a braking system (5), an electromechanical brake force amplifier (7) having an amplifier control device (9), a driving stability control device (10), the driving stability control device being configured to influence the braking system (5) in accordance with a current driving state of the motor vehicle (1) in order to stabilize the driving state, and a communication network (11), the engine control device (3), the amplifier control device (9), and the driving stability control device (10) communicating with one another via the communication network, characterized in that: The amplifier control unit (9), the driving stability control unit (10) and / or the engine control unit (3) are designed to carry out the method according to any one of claims 1 to 5.

7. The motor vehicle according to claim 6, characterized in that The driving stability control device (10) has at least one acceleration sensor, speed sensor or rotational speed sensor.

8. The motor vehicle according to any one of claims 6 and 7, characterized in that The communication network (11) is a bus system.

9. The motor vehicle according to any one of claims 6 and 7, characterized in that Means are present for determining activation of the braking system.

10. The motor vehicle according to claim 9, characterized in that The device is a door lock or door contact (12).

Images