Electrical circuit for supplying power to an airbag control unit

Abstract

Electrical circuit (1) for supplying voltage to an airbag control unit (2) from a battery in a battery-electric vehicle, wherein a positive pole (KL30) of a low-voltage battery can be switched to a voltage supply input of the airbag control unit (2) via a relay (4), characterized in that an ignition plus signal (KL15) and an activation signal (UE) of a high-voltage system form a logical OR operation for controlling the relay (4) by means of respective diodes (D1, D2).

Description

[0001] The invention relates to an electrical circuit for supplying voltage to an airbag control unit according to the preamble of claim 1.

[0002] In the event of an accident involving a vehicle that is not fully or partially electrified, an airbag control unit is kept active using the ignition, for example terminal 15, to ensure that the airbag is deployed.

[0003] In a battery-electric vehicle, particularly a commercial vehicle, the components of a high-voltage system are activated via a Unit Enable signal line. This allows the high-voltage system to be activated even when the vehicle is stationary, particularly during charging and preconditioning. The Unit Enable signal in battery-electric vehicles is also sometimes used to initiate an active discharge function of so-called brake choppers, i.e., the electrical equivalent of a retarder, a wear-free continuous brake comprising power resistors.

[0004] In the event of a collision, however, the components of the high-voltage system must be deactivated. However, the airbag control unit must be active in both cases, for example, in the event of a second accident without prior airbag deployment and without affecting the other functions. This means that simultaneous control of the active discharge function of the brake chopper and the supply of power to the airbag control unit via the unit enable signal is not possible.

[0005] DE 10 2015 209 925 A1 describes a high voltage shutdown system and method for an electric vehicle that performs a high voltage shutdown function in association with a collision detection signal (airbag expansion signal) generated by an airbag controller, even when a vehicle is being charged. The high voltage shutdown system includes a third power supply controller that is in an operative state to transmit power when the vehicle is started and charged. An airbag control unit is actuated by receiving power from the third power supply controller and is configured to generate an airbag expansion signal upon detecting an occurrence of a collision of the vehicle. A high voltage controller is configured to perform a high voltage shutdown function in response to receiving the airbag expansion signal.

[0006] The invention is based on the object of providing a novel electrical circuit for supplying voltage to an airbag control unit.

[0007] The object is achieved according to the invention by an electrical circuit for supplying voltage to an airbag control unit according to claim 1.

[0008] Advantageous embodiments of the invention are the subject of the subclaims.

[0009] An electrical circuit according to the invention for supplying voltage to an airbag control unit from a battery in a battery-electric vehicle is designed such that a positive pole of a low-voltage battery can be switched to a voltage supply input of the airbag control unit via a relay, wherein an ignition plus signal and an activation signal of a high-voltage system form a logical OR operation for controlling the relay by means of respective diodes.

[0010] The inventive solution complies with legal requirements. Furthermore, the invention is easy to implement. Only a relay is used as an additional component. Furthermore, relays are very inexpensive to purchase because they are already fully marketable and widely used. The airbag remains functional even while charging. Furthermore, the diodes make the system suitable for secondary accidents. This means that if, for example, only the passenger airbag and not the driver airbag is deployed in a minor accident, the driver airbag or any other airbag can still be deployed in a subsequent accident, for example due to uncontrolled driving conditions or an uncontrolled change of direction and impact with another object. In any case, the safety of the occupants in the vehicle is increased, especially in the event of a secondary accident.

[0011] Embodiments of the invention are explained in more detail below with reference to a drawing.

[0012] It shows: Fig. 1 a schematic diagram of an electrical circuit for supplying voltage to an airbag control unit from a battery in a battery-electric vehicle.

[0013] The invention relates to an electrical circuit 1 which enables a simultaneous supply of an airbag control unit 2 for at least one airbag 5 and a control of an active discharge function of at least one brake chopper BRC in a battery-electric vehicle in order to thus comply with legal requirements.

[0014] According to the invention, this is achieved by a signal at terminal 15 KL15 (ignition plus, switched plus) and an activation signal Unit Enable UE (activation of the high-voltage system) forming a logical OR operation via respective diodes D1, D2 to control a relay 4. This OR operation of the diodes D1, D2 is necessary because otherwise the signals KL15 and UE would cancel each other out. Relay 4 switches a signal at terminal 30 KL30 (battery plus, positive terminal of a low-voltage battery with, for example, 12 V) as a voltage supply to the airbag control unit 2. This ensures the function of the airbag control unit 2 even during charging.

[0015] Since in the event of a minor accident or impact that only affects the high-voltage system, the activation signal Unit Enable UE is switched off in order to implement the active discharge function of the Brake Chopper BRC, the function of Airbag Control Unit 2 would no longer be available. In accordance with legal requirements, the Brake Chopper BRC must be redundantly switched off via a signal at terminal 30c KL30c (analog crash signal) and the activation signal Unit Enable UE. This means that in the event of a subsequent more serious accident or impact, Airbag 5 cannot be deployed because Airbag Control Unit 2 would not be supplied with voltage. For this reason, an alternative control using the signal at terminal 15 KL15 is provided. However, Airbag Control Unit 2 cannot be controlled solely with the signal at terminal 15 KL15, since this is not active during a charging process and thus Airbag Control Unit 2 can only be controlled via the activation signal Unit Enable UE.Control via the signal at terminal 15 KL15 is only possible while driving. In the event of a collision or accident, the Unit Enable UE activation signal can be deactivated, and relay 4 is maintained by the signal at terminal 15 KL15, ensuring continued power supply to airbag control unit 2.

[0016] In addition, multiple use of the activation signal Unit Enable UE and a possible linking with other signals is possible for the brake chopper BRC, an electric power take-off system ePTO (electric power take-off) and the airbag control unit 2.

[0017] The signal terminal 30c KL30c is connected to the signal terminal 30 KL30 via a pyrofuse 3 that can be triggered by the airbag control unit 2 and an emergency stop button 6. List of reference symbols 1 electrical circuit 2 Airbag control unit 3 Pyrofuse 4 relays 5 airbags 6 emergency stop buttons BRC Brake Chopper D1 diode D2 diode ePTO electric power take-off system KL15 Signal Terminal 15, ignition plus signal KL30 Signal terminal 30, positive pole KL30c signal terminal 30c, analog crash signal UE Signal Unit Enable, activation signal

Claims

[1] Electrical circuit (1) for supplying voltage to an airbag control unit (2) from a battery in a battery-electric vehicle, wherein a positive terminal (KL30) of a low-voltage battery can be switched to a voltage supply input of the airbag control unit (2) via a relay (4), characterized by that an ignition plus signal (KL15) and an activation signal (UE) of a high-voltage system form a logical OR link for controlling the relay (4) by means of respective diodes (D1, D2). [2] Electrical circuit (1) according to claim 1, characterized by that a brake chopper (BRC) of a battery-electric vehicle is provided, which can be switched off redundantly via an analog crash signal (KL30c) and the activation signal (UE), wherein the analog crash signal (KL30c) is connected to the positive pole (KL30) via a pyrophoresis device (3) that can be triggered by the airbag control unit (2) and can be switched off via an emergency stop button (6).

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