Brake assist system for a vehicle

Abstract

Brake assist system (10) for a vehicle (1), comprising - a brake control unit (12) with which a control signal can be received, indicating whether a collision has occurred, and with which a brake signal for the brakes (3) of the vehicle (1) can be generated depending on the received control signal, and - a main power supply (5) which is connected to the brake control unit (12) and supplies it with power, - a detection device (4) for receiving and evaluating sensor signals from at least one sensor (7), wherein the control signal indicating whether a collision has occurred can be output from the detection device (4), and wherein the brake control unit (12) is coupled to the detection device (4) via a data connection (11), characterized in that - the brake control unit (12) is connected to an emergency power supply (21) by means of which the brake control unit (12) can be supplied with energy if the main power supply (5) has failed, - wherein the brake assist system (10) comprises a further data connection (24) which couples the detection device (4) to the brake control unit (12), wherein the further data connection (24) is physically independent of the data connection (11), and wherein the control signal or a further control signal issued by the detection device (4) can be received by the brake control unit (12) via the further data connection (24).

Description

[0001] The present invention relates to a brake assistance system for a vehicle comprising a brake control unit capable of receiving a control signal indicating whether a collision has occurred and generating a braking signal for the vehicle's brakes based on the received control signal. The brake control unit is connected to a main power supply that supplies the brake control unit with power.

[0002] A vehicle's brakes are used to reduce the vehicle's speed and, if necessary, to bring the vehicle to a stop or hold it stationary. Typically, the driver can apply a brake pedal. This application is transmitted to the vehicle's brakes to generate braking torque. The driver's application force can be amplified by suitable means.

[0003] Furthermore, it is known to control the vehicle's driving dynamics. An electronic stability program (ESP or Electronic Stability Control: ESC) is used for this purpose. Vehicle dynamics control prevents the vehicle from skidding sideways by selectively braking individual wheels. Furthermore, vehicle dynamics control is used to prevent multiple collisions. In a multiple collision, two or more collisions between the vehicle and other objects occur at different times. Such multiple collisions can be partially avoided, or their effects mitigated, if the vehicle is braked appropriately immediately after the first collision.

[0004] The consequences of an accident are particularly mitigated, or there is a particularly high chance of avoiding a second collision, in cases where the first collision is only a "minor" collision, e.g. a collision between a vehicle and a guardrail at a shallow angle. After such a collision, the driver is often no longer able to control the vehicle, so that the vehicle collides uncontrollably with another vehicle or other objects in the vehicle's vicinity. If, on the other hand, the vehicle is automatically braked after the first collision by a suitable brake assistance system, the probability increases that the driver will be able to regain control of the vehicle and / or that the vehicle will come to a stop before it collides with another object.

[0005] For example, DE 10 2010 055 943 A1 discloses a method for operating a vehicle in which, in the event of a detected collision, the vehicle is automatically braked. If the vehicle then continues to move unintentionally in this case, the method automatically brakes it.

[0006] Furthermore, DE 10 2011 108 870 A1 discloses a method for preventing secondary accidents and reducing their severity. This method first detects a primary accident, for example, by deploying an airbag. Once an accident is detected, a previously deactivated lane guidance device is automatically activated above a defined speed threshold, keeping the vehicle in the lane or at least on the roadway.

[0007] Furthermore, DE 10 2010 035 197 A1 discloses a method for controlling a brake assistance system of a vehicle and such a brake assistance system, in which sensor signals from a sensor are converted into a control signal, and the control signal is transmitted to a brake control unit via a first connection. The control signal indicates whether an accident has occurred. This control signal or another control signal indicating whether an accident has occurred is transmitted via a second connection, which is physically independent of the first connection, to the brake control unit, which then generates a brake control signal depending on the control signals received via the two connections.

[0008] WO 2011 / 054 668 A1 describes a method for performing an emergency braking operation using a braking system in a vehicle. In the event of an emergency situation, at least one electric actuator in the braking system is automatically activated to generate increased braking force. To ensure this function, an additional energy storage device is provided, which is powered by the battery during normal operation.

[0009] DE 10 2007 043 578 A1 describes a device for recovering kinetic energy from a moving vehicle using a generator-operated electric motor in at least one wheel of the vehicle. This generator operation is intended to supply power to safety-relevant components, such as the braking system, in an emergency.

[0010] DE 10 2010 035 197 A1 describes a method for controlling a brake assistance system of a vehicle, in which sensor signals from at least one first sensor are converted into at least one control signal, and the control signal is transmitted via a first connection to a brake control unit. The control signal indicates whether an accident has occurred. For this purpose, the signals from two sensors in the airbag and the evaluation of the airbag control unit are used.

[0011] DE 197 42 988 C1 describes a braking system for a motor vehicle in which the central control unit is connected to the brake actuators via a first data transmission channel and a second data transmission channel. This is intended to ensure that, in the event of a CPU failure, the actuators can continue to be supplied with power, thus enabling emergency braking.

[0012] It has now been shown that existing brake assistance systems are particularly effective for moderate-severity collisions, such as collisions with guardrails. It has been shown that improvements to existing brake assistance systems are desirable for severe collisions, such as a head-on collision at approximately 50 km / h.

[0013] The present invention is therefore based on the object of specifying a brake assistance system for a vehicle of the type mentioned above, in which the occurrence of multiple collisions is reliably prevented in the event of a severe primary collision.

[0014] According to the invention, this object is achieved by a brake assistance system having the features of claim 1. Advantageous embodiments and further developments emerge from the dependent claims.

[0015] The invention is based on the knowledge that in serious collisions short circuits occur in larger power consumers, such as the starter of the generator. This is caused, for example, by the front of the vehicle being pushed in. As a result of these short circuits, the vehicle electrical system voltage collapses briefly, so that the main power supply fails for this period. Protective devices then disconnect the short-circuited consumers from the vehicle electrical system, so that the period for which the main power supply fails is shorter than 1 second. However, this short time interval in which the main power supply fails is sufficient to cause the brake control unit to go through a reset. The time required for this reset is much longer than the time interval in which the main power supply failed.During this longer time interval, the brake control unit cannot generate braking signals for the vehicle's brakes and therefore cannot take any measures to prevent multiple collisions.

[0016] In view of this finding of the inventors, the brake assistance system specified at the outset was further developed in such a way that the brake control unit is connected to an emergency power supply by means of which the brake control unit can be supplied with power if the main power supply has failed.

[0017] The emergency power supply of the braking system according to the invention advantageously not only ensures that the brake control unit remains operational even during a failure of the main power supply. Rather, it also prevents the brake control unit from undergoing a reset in the event of a brief failure of the main power supply, which would prevent it from generating a braking signal to prevent multiple collisions for an extended period of time.

[0018] The emergency power supply is, for example, a storage device for electrical energy. This storage device can be connected to the main power supply, so that the emergency power supply can be charged via the main power supply. The emergency power supply thus advantageously provides a buffer that can ensure the function of the brake control unit with relatively little effort in the event of a brief failure of the main power supply. This, in particular, prevents the brake control unit from going through a reset.

[0019] According to one embodiment of the brake assistance system according to the invention, it comprises a brake force generator coupled to the brake control unit and the main power supply, so that a braking force for the vehicle's brakes can be generated depending on the braking signal. The braking force generator can comprise, for example, hydraulic or pneumatic devices. In the event of a failure of the main power supply, this braking force generator cannot generate braking force for the brakes, but the main power supply is very quickly restored in such a case, so that immediately after the full vehicle electrical system voltage is restored, the braking signal from the brake control unit leads to the generation of braking force for the brakes.

[0020] In order not only to ensure the functionality of the brake assistance system immediately after the full vehicle electrical system voltage is restored, it can further be provided according to the invention that the brake force generator is also connected to the emergency energy supply, by means of which the brake force generator can also be supplied with energy if the main energy supply has failed.

[0021] If the emergency power supply is provided only for the brake control unit of the brake assistance system, a cost-effective and weight-saving improvement of the brake assistance system can be advantageously achieved. If the emergency power supply is also provided for the brake force generator, the emergency power supply must be designed to cover a much higher power requirement, since in this case, motors and pumps may also have to be supplied with power from the emergency power supply. This results in higher costs and greater weight. However, the full functionality of the brake assistance system is advantageously ensured even during a failure of the main power supply.

[0022] The brake assistance system according to the invention comprises a detection device for receiving and evaluating sensor signals from at least one sensor. This detection device can output the control signal indicating whether a collision has occurred. According to the invention, the brake control unit is coupled to the detection device via a data connection. This data connection can be a data bus of the vehicle, in particular the CAN (Controller Area Network) bus. This detection device is, in particular, an airbag control unit. Advantageously, such an airbag control unit is already present in the vehicle for controlling an airbag. The function of the airbag control unit can thus be used in the brake assistance system according to the invention to generate the control signal for the occurrence of the collision.This advantageously ensures that the brake assistance system according to the invention can be implemented in a vehicle in a cost-effective and weight-saving manner.

[0023] In the event of a serious collision, however, the problem arises that if the main power supply fails, data transmission via a vehicle data bus may also fail. For this reason, the invention provides that the brake assistance system comprises an additional data connection which couples the detection device to the brake control unit, wherein the additional data connection is physically independent of the data connection via the vehicle data bus. The additional data connection can be a robust direct line between the detection device and the brake control unit, which is laid in such a way that it is not damaged even in the event of a serious collision with the vehicle. Furthermore, the additional data connection could also be implemented via wireless data transmission, which is not impaired even in the event of a serious collision with the vehicle.The control signal can be transmitted redundantly to the brake control unit via the additional data connection in order to secure the data transmission via the first data connection.

[0024] The brake control unit can, for example, be a control unit for the vehicle's driving dynamics control system. Such a brake control unit is often already present in a vehicle for the vehicle's driving dynamics control. In this way, the brake assistance system according to the invention can be implemented in a vehicle in a cost-effective and lightweight manner.

[0025] The invention further relates to a motor vehicle with the brake assistance system described above.

[0026] The invention will now be explained using an embodiment with reference to the drawings. Fig. 1 shows a vehicle with an embodiment of the brake assistance system according to the invention and Fig. 2 shows the structure of the embodiment of the brake assistance system according to the invention.

[0027] In Fig. Figure 1 shows the vehicle, in particular the motor vehicle, in which the exemplary embodiment of the brake assistance system 10 is installed. Such a vehicle 1 is known per se. It has wheels 2 that can be braked via brakes 3.

[0028] With reference to Fig. 2, details of the embodiment of the brake assistance system 10 are explained below: The brake assistance system 10 includes an airbag control unit 4, which serves as a detection device for the occurrence of a collision. During operation, the airbag control unit 4 is supplied with power via the main power supply 5 of the vehicle 1. For this purpose, it is connected to the main power supply 5 via the electrical line 6.

[0029] The airbag control unit 4 is coupled to several sensors 7. The measurement signals from the sensors 7 are transmitted to the airbag control unit 4, which evaluates these measurement signals and thus determines whether a collision has occurred. Depending on the severity of the collision, the airbag control unit 4 actuates safety devices 8 of the vehicle 1, such as an airbag and / or a belt tensioner of the vehicle 1, in a manner known per se.

[0030] Furthermore, the airbag control unit 4 is connected to a data bus 11 of the vehicle 1 via a data connection 9. If a collision is detected by the airbag control unit 4, the airbag control unit 4 outputs a corresponding control signal to the data bus 11. The data bus 11 is also supplied with power via an electrical line 25 from the main power supply 5 of the vehicle 1.

[0031] The brake assistance system 10 further includes a brake control unit 12. This control unit 12 is the control unit that also serves for the vehicle dynamics control (ESC) of the vehicle 1. The brake control unit 12 is connected to the main power supply 5 of the vehicle 1 via the electrical line 13. Furthermore, the brake control unit 12 is coupled to the data bus 11 via the data connection 14, so that it can receive the control signal transmitted by the airbag control unit 4 for the occurrence of a collision.

[0032] The brake control unit 12 is coupled via the data connection 15 to a brake force generator comprising a motor 16 and a hydraulic device 17, so that a braking force for the brakes 3 of the vehicle 1 can be generated via the line 20. The hydraulic device 17 comprises several valves and pumps. The motor 16 and the hydraulic device 17 are also connected to the main power supply 5 of the vehicle 1 via the electrical lines 18 and 19.

[0033] The brake assistance system 10 described above is known per se. The following describes the function of this brake assistance system 10 in the event of a minor collision, e.g., with a guardrail: The minor collision is detected by the airbag control unit 4 using the measurement signals from sensors 7. The airbag control unit 4 then transmits a control signal to trigger the multi-collision brake on the data bus 11 via the data connection 9. The data bus 11 forwards this control signal to the brake control unit 12, which receives it. The brake control unit 12 then generates a brake signal or several consecutive brake signals to initiate the multi-collision brake. Based on these brake signals, the motor 16 and the pumps of the hydraulic system 17 start up and build up pressure for the brakes 3 via line 20. The vehicle 1 is thus braked.

[0034] In a severe collision, such as a head-on collision at 50 km / h, the main power supply 5 may briefly fail. In this case, neither the data bus 11 nor the brake control unit 12 can be supplied with power. The airbag control unit 4 can remain functional if an emergency power supply 23 is interposed in the electrical line 6. This emergency power supply 23 can supply the airbag control unit 4 with power during a brief failure of the main power supply 5. However, neither the control signal of the airbag control unit 4 is transmitted from the data bus 11 to the brake control unit 12, nor is the brake control unit 12 functional during the time interval of the failure of the main power supply 5. This causes the brake control unit 12 to undergo a reset.Such a reset process of the brake control unit 12 takes considerably longer than the usual time interval during which the main power supply 5 failed. For this reason, the brake control unit 12 cannot generate and transmit the braking signal to the brake force generator, even when the electrical voltage of the main power supply 5 is reapplied. The pressure buildup for the brakes 3 of the vehicle 1 thus only occurs once the brake control unit 12 has completed the complete reset, i.e., not until considerably later than the time at which the failure of the main power supply 5 was remedied.

[0035] For this reason, the following changes to a conventional brake assistance system are made in the brake assistance system 10 according to the invention: The airbag control unit 4 is directly coupled to the brake control unit 12 via a data connection 24. The data connection 24 is physically independent of the data bus 11. The data connection 24 is designed in particular so that it is not affected even by a severe collision. This ensures that even in the event of a severe collision, the functional airbag control unit 4 transmits a control signal to the brake control unit 12, indicating that a collision has occurred.

[0036] Furthermore, an emergency power supply 21 is provided in the electrical line 13, which connects the brake control unit 12 to the main power supply 5. This emergency power supply 21 is designed to supply at least the brake control unit 12 with power if the main power supply 5 fails for a short time. Optionally, the emergency power supply 21 can also be designed to supply the motor 16 and the hydraulic device 17 with power via the electrical line 22 if the main power supply 5 fails for a short time. The emergency power supply 21 is thus a buffer that is continuously charged with electrical energy from the main power supply 5 during normal operation.If the main power supply 5 fails, the electrical energy stored in the emergency power supply 21 is discharged and made available to the brake control unit 12 and, if applicable, to the motor 16 and the hydraulic device 17.

[0037] In this case, if the main power supply 5 briefly fails during a serious collision involving vehicle 1, the power supply to data bus 11 is interrupted, but the airbag control unit 4 can still transmit a control signal to the brake control unit via data connection 24, indicating that a collision has occurred. Due to the emergency power supply 21, the brake control unit 12 is continuously supplied with power, even if the main power supply 5 has briefly failed. This prevents the brake control unit 12 from undergoing a reset. The brake control unit 12 can therefore continue to process the control signal transmitted by the airbag control unit 4 and generate a brake signal for the motor 16 and the hydraulic device 17.However, if the motor 16 and the hydraulic device 17 are not connected to the emergency power supply 21 via the electrical line 22 because the latter cannot provide sufficient power for the brake force generator, the motor 16 and the hydraulic device 17 will immediately convert the brake signal from the brake control unit 12 and generate a braking force for the brakes 3 after the power supply from the main power supply 5 is restored. The brake force generator therefore does not have to wait until the brake control unit has undergone a reset.

[0038] If, however, the motor 16 and the hydraulic device 17 are also connected to the emergency power supply 21 or another emergency power supply via the line 22, they can convert the braking signal transmitted by the brake control unit 12 at any time, in particular regardless of a failure of the main power supply 5, and generate the braking force for the brakes 3. List of reference symbols 1 vehicle 2 wheels 3 brakes 4 Airbag control unit; detection device 5 Main energy supply 6 electrical cable 7 sensors 8 Safety devices 9 Data connection 10 Brake assistance system 11 Data bus 12 Brake control unit 13 electrical cable 14 Data connection 15 Data connection 16 Engine 17 hydraulic device 18 electrical cable 19 electrical cable 20 Line 21 Emergency power supply 22 electrical cable 23 Emergency power supply 24 Data connection 25 electrical cables

Claims

[1] Brake assistance system (10) for a vehicle (1), comprising - a brake control unit (12) with which a control signal can be received which indicates whether a collision has occurred and with which a brake signal for the brakes (3) of the vehicle (1) can be generated in dependence on the received control signal, and - a main power supply (5) which is connected to the brake control unit (12) and supplies it with power, - a detection device (4) for receiving and evaluating sensor signals from at least one sensor (7), wherein the control signal indicating whether a collision has occurred can be output by the detection device (4), and wherein the brake control unit (12) is coupled to the detection device (4) via a data connection (11), characterized by , that - the brake control unit (12) is connected to an emergency power supply (21) by means of which the brake control unit (12) can be supplied with power if the main power supply (5) has failed, - wherein the brake assistance system (10) comprises a further data connection (24) which couples the detection device (4) to the brake control unit (12), wherein the further data connection (24) is physically independent of the data connection (11), and wherein the or a further control signal output by the detection device (4) can be received by the brake control unit (12) via the further data connection (24). [2] Brake assistance system (10) according to claim 1, characterized by that the emergency power supply (21) is a storage facility for electrical energy. [3] Brake assistance system (10) according to claim 2, characterized bythat the storage of the emergency energy supply (21) is connected to the main energy supply (5) so that the emergency energy supply (21) can be charged by means of the main energy supply (5). [4] Brake assistance system (10) according to one of the preceding claims, characterized by that the brake assistance system (10) comprises a brake force generator (16, 17) which is coupled to the brake control unit (12) and the main energy supply (5) so that a braking force for the brakes (3) of the vehicle (1) can be generated as a function of the braking signal, and that the brake force generator (16, 17) is connected to the emergency energy supply (21), by means of which the brake force generator (16, 17) can be supplied with energy if the main energy supply (5) has failed. [5] Brake assistance system (10) according to claim 4, characterized by that the braking force generator (16, 17) comprises a hydraulic or pneumatic device (17). [6] Brake assistance system (10) according to claim 1, characterized by that the detection device (4) is an airbag control unit. [7] Brake assistance system (10) according to one of the preceding claims, characterized by that the brake control unit (12) is a control unit of the driving dynamics control of the vehicle (1). [8] Motor vehicle (1) with a brake assistance system (10) according to one of the preceding claims.

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