Immobilizer device for a motor vehicle, motor vehicle and procedure for operating an immobilizer device

Abstract

Immobilizer arrangement (4) of a motor vehicle (2) comprising a parking brake (6) which can be electrically actuated by at least one motor (18), wherein the at least one motor (18) is controlled by a brake control (20), and an immobilizer control (12) arranged separately from the parking brake (6) for activating and deactivating the immobilizer of the motor vehicle (2), wherein the immobilizer control (12) is configured to receive authorization via a user identification device (14) and, upon successful authorization, to disable the immobilizer, wherein the parking brake (6) serves as the immobilizer, wherein the parking brake (6) and the immobilizer control (12) are connected to each other via a two-wire cable (28) to provide a supply voltage for the parking brake (6), wherein a microcontroller (22) for controlling the at least one motor (18) is provided in the parking brake (6).wherein the immobilizer control unit (12) is configured to modulate a coded signal (32) onto the supply voltage, wherein the microcontroller (22) is configured to check the coded signal (32) and to allow activation of the at least one motor (18) only after successful testing.

Description

[0001] This document describes an immobilizer device, a motor vehicle, and a procedure for operating an immobilizer device.

[0002] Immobilizers are devices on motor vehicles designed to prevent them from being operated without authorization.

[0003] In many countries, electronic immobilizers are legally required. These electronic immobilizers include, among others, so-called three-circuit interruptions, which bypass the ignition, fuel supply, and starter using a relay. Furthermore, there are electronic immobilizers that intervene in the engine control unit and issue a release signal without which the engine will not start. Communication of these release signals usually takes place via the vehicle's bus system and is encrypted. Immobilizers are often unlocked by radio transmitters, which are typically integrated into the vehicle's keys (in the colloquial sense), acting as transponders. This communication can be encrypted or unencrypted.

[0004] Immobilizers can also include a mechanical component, for example a locking device for a steering wheel controlled by the immobilizer control unit, which prevents the steering of the corresponding motor vehicle from being operated.

[0005] The inclusion of a mechanical immobilizer necessitates increased vehicle complexity, which increases the development effort as well as the cost of a suitably equipped vehicle.

[0006] DE 10 2016 004 218 A1 describes an immobilizer arrangement for a motor vehicle, comprising a brake that can be electrically actuated by at least one motor, wherein the at least one motor is controlled by a brake control unit, and an immobilizer control unit for activating and deactivating the immobilizer of the motor vehicle, which is designed to receive authorization via a user identification device for overriding the immobilizer, wherein the brake serves as an immobilizer, wherein at least one current path is provided for actuating the motor, which is coupled to the immobilizer control unit, and wherein a filter circuit is integrated into at least one brake caliper and / or the motor of the brake.

[0007] The filter circuit described above is integrated into the vehicle communication system via a bus system. This increases the design and manufacturing effort.

[0008] The task therefore is to further develop immobilizer systems, motor vehicles and procedures for operating an immobilizer system of the type mentioned above in such a way that a more cost-effective mechanical immobilizer solution is possible than before.

[0009] The problem is solved by an immobilizer device according to claim 1, a motor vehicle according to dependent claim 5, and a method for operating an immobilizer device according to dependent claim 6. Further embodiments and developments are the subject of the dependent claims.

[0010] The following describes an immobilizer arrangement for a motor vehicle with a parking brake that can be electrically actuated by at least one motor, wherein the at least one motor is controlled by a brake control unit, and an immobilizer control unit arranged separately from the parking brake for activating and deactivating the immobilizer of the motor vehicle, wherein the immobilizer control unit is configured to receive authorization via a user identification device and, upon successful authorization, to deactivate the immobilizer, wherein the parking brake serves as the immobilizer, wherein the parking brake and the immobilizer control unit are connected to each other via a two-wire cable to provide a supply voltage for the parking brake, wherein a microcontroller for controlling the at least one motor is provided in the parking brake, and wherein the immobilizer control unit is configured toto modulate a coded signal onto the supply voltage, wherein the microcontroller is designed to check the coded signal and only allow activation of at least one motor after successful testing.

[0011] A supply voltage provides the energy necessary for operation, whereas a diagnostic voltage is used for system testing. Diagnostic voltages typically have lower voltage amplitudes than supply voltages and higher impedance.

[0012] The immobilizer arrangement described here eliminates the need to connect the parking brake to a bus system for communication with an immobilizer control unit, thus reducing the cost of such an arrangement. Furthermore, the immobilizer arrangement described here is tamper-proof, making it considerably more difficult to bypass the immobilizer.

[0013] Many motor vehicles already feature electrically operated parking brakes. The corresponding motor, often called an actuator, can be centrally located for several brakes, for example, both rear axle brakes, with the brakes frequently connected to the motor via a cable. Alternatively, braking systems are also known in which one actuator is assigned to a single wheel brake. It is known to arrange such actuators directly on or in the brake caliper. Such systems are generally used in addition to hydraulic braking systems.

[0014] By coupling the corresponding motor that actuates the brake with the immobilizer control unit, the brake can be used as a mechanical immobilizer, thus preventing the vehicle from being moved. The additional component complexity of such a solution is minimal. Because the current path is controlled by the microcontroller, the current flow necessary to release the brake can be kept interrupted as long as no release signal is present. When a release signal is received, after authorization via the user identification device to deactivate the immobilizer, the brake can be released, allowing the vehicle to be driven away. The microcontroller is integrated into the parking brake mechanism.

[0015] A corresponding user identification device can, for example, be in the form of a transmitter, particularly a radio transmitter. Such a radio transmitter can also perform other functions, such as unlocking or locking the door locks of a vehicle and authorizing the vehicle to start. These radio transmitters are commonly referred to as keys. Authorization can be unencrypted or, in particular, encrypted, and can be received by the immobilizer control unit in a suitable manner, depending on the transmission path, for example, via a bus system. This allows the immobilizer to release the power path for actuating the brake motor.

[0016] In a first further embodiment, it can be provided that the microcontroller is arranged together with the motor in a housing of the parking brake.

[0017] Encapsulating the motor and microcontroller in a single housing prevents or at least significantly hinders unauthorized power supply to the motor. Such parking brakes are usually designed either as an actuator module, in which case a suitable microcontroller according to the present design can be integrated into the module, or as a motor within the brake caliper, in which case a suitable microcontroller according to the present design can be integrated either into a motor housing or into a brake caliper.

[0018] In a further development, the microcontroller can be encapsulated, so that non-destructive access to the microcontroller is impossible.

[0019] In another, more advanced embodiment, the microcontroller can be connected to an energy storage device, in particular a capacitor, to supply power to the microcontroller. This allows the microcontroller to remain active for a period of time without an external power supply, for example, to bridge periods without power, such as when the brake control switches from one control phase to the next. Once the energy stored in the energy storage device is depleted, the microcontroller becomes inactive.

[0020] In another further embodiment, the microcontroller can be connected to a switch, the microcontroller being configured to actuate the switch. In a first position, the switch interrupts the current flow between the brake control unit and the motor, while in a second position, the switch allows current flow between the brake control unit and the motor. In this way, the microcontroller can prevent the motor from being actuated without disabling the immobilizer. The switch can be, for example, a MOSFET, relay, or similar device.

[0021] A first independent item concerns a motor vehicle with an immobilizer device of the aforementioned type.

[0022] Another independent subject matter relates to a method for operating an immobilizer arrangement of the aforementioned type, wherein the immobilizer arrangement is unlocked by a user identification device, wherein an immobilizer control unit transmits a coded signal via a two-wire cable, which provides a supply voltage for a parking brake, to a brake control unit of the parking brake, wherein the coded signal is modulated onto the supply voltage, wherein a microcontroller in the brake control unit checks the coded signal and, if the check is successful, enables the control of a motor of the parking brake to release the parking brake.

[0023] A first further development of the procedure provides that a wake-up voltage is supplied by means of the immobilizer control before the coded signal is transmitted, so that the microcontroller can start or boot up.

[0024] According to another further embodiment of the method, the microcontroller can be provided with a charge charge storage device, in particular a capacitor. In this way, the microcontroller can bridge periods without power, e.g., to remain operational during a change in different operating phases of the immobilizer control.

[0025] In another, more advanced embodiment, the coded signal can be transmitted in the form of a voltage waveform or a PWM signal. Corresponding coding methods function reliably and can be applied to operating or supply voltages or diagnostic voltages.

[0026] In another, more advanced embodiment, the microcontroller can be configured to store the coded signal from the immobilizer control unit upon initial startup. This allows for easy pairing of the immobilizer control unit and the microcontroller during production.

[0027] Another independent item relates to a device for operating an immobilizer arrangement, in particular an immobilizer arrangement of the aforementioned type, wherein an unlocking device for unlocking the immobilizer arrangement by means of a user identification device is provided, wherein a transmission device for sending a coded signal from the immobilizer control to a brake control is provided, wherein a microcontroller is provided in the brake control which is configured to check the coded signal, wherein the microcontroller is configured to enable, upon successful testing, the activation of a motor of the parking brake to release the parking brake.

[0028] In a first further embodiment, it may be provided that a device for providing a wake-up voltage is included in order to start the microcontroller before transmitting the coded signal.

[0029] Furthermore, in a further embodiment, an energy storage device, in particular a capacitor, can be provided, wherein the microcontroller is configured to charge the energy storage device.

[0030] In another further embodiment, a device may be provided which is designed to transmit the coded signal in the form of a voltage waveform or a PWM signal.

[0031] In a further, more advanced embodiment, it may be provided that the microcontroller is configured to store the coded signal of the immobilizer control unit upon initial commissioning.

[0032] Further features and details will become apparent from the following description, in which – possibly with reference to the drawing – at least one embodiment is described in detail. The features described and / or illustrated constitute the subject matter individually or in any meaningful combination, possibly also independently of the claims, and may in particular also be the subject matter of one or more separate applications. Identical, similar, and / or functionally equivalent parts are designated with the same reference numerals. These are shown schematically: Fig. 1 a motor vehicle equipped with an immobilizer device, as well as Fig. 2A - 2E the immobilizer arrangement from Fig. 1 in several phases of operation.

[0033] Fig. Figure 1 shows a motor vehicle 2 with an immobilizer device 4 (outlined by a dashed line).

[0034] The immobilizer assembly 4 acts on the rear wheel brakes 6. One rear wheel brake 6 is provided for each wheel. The rear wheel brakes 6 each have brake calipers 8, which can be actuated hydraulically as service brakes and also by means of a motor unit 10.

[0035] The motor units 10 enable the rear wheel brakes 6 to be used as a parking brake. The parking brake is used to park the motor vehicle 2 and prevent it from rolling away. For this purpose, the respective motor unit 10 is actuated in a closing direction to press the brake shoes of the rear wheel brakes 6 against the corresponding brake discs or drums. To move the motor vehicle 2, it is necessary to release the rear wheel brakes 6, for which the motor unit 10 must be actuated in an opening direction.

[0036] Furthermore, depending on the equipment of the motor vehicle 2, the motor units 10 can be used to implement a roll-back protection system when starting off.

[0037] The motor units 10 are connected to an immobilizer control unit 12, which prevents the rear wheel brakes 6 from being released as long as the immobilizer is not unlocked. When the vehicle 2 is parked, the immobilizer control unit 12 causes the rear wheel brakes 6 to be applied by means of the motor units 10. This can be done, for example, by means of a user identification device 14 (remote key).

[0038] The Fig. Figures 2A to 2E show the immobilizer arrangement 4 in different operating phases. Energized lines are shown as solid lines, de-energized lines as dashed lines.

[0039] Fig. 2A shows the immobilizer arrangement 4 in an initial state before the immobilizer is released at time t0.

[0040] The motor unit 10 has a housing 16 in which a motor 18, a brake control 20 (shown outlined with dashed lines) and a microcontroller 22 are arranged.

[0041] The microcontroller 22 controls a switch 24, which enables or prevents a current flow to the motor 18.

[0042] The microcontroller 22 is also connected to a capacitor 26, which can be charged by the microcontroller 22.

[0043] The immobilizer control unit 12 is connected to the engine unit 10 via a two-core cable 28.

[0044] Fig. Figure 2B shows the immobilizer arrangement 4 after a wake-up phase at time t1.

[0045] At this point, the immobilizer control unit 12 has provided a wake-up voltage 30, which is sufficient to power up the microcontroller 22. Furthermore, the microcontroller has received enough energy from the wake-up voltage 30 to charge the capacitor 26.

[0046] Fig. 2C shows the immobilizer arrangement 4 during the release of the immobilizer at time t2.

[0047] The immobilizer control unit 12 has generated a unique coded signal 32 and transmitted it to the brake control unit 20 via the two-wire cable 28. The coded signal 32 is read by the microcontroller 22 and compared with a signal stored in the microcontroller 22.

[0048] If the coded signal 32 matches the signal stored in the microcontroller 22, the switch 24 is actuated by the microcontroller 22 so that the motor 18 can be powered to release the rear wheel brake 6.

[0049] Fig. 2D shows the immobilizer arrangement 4 during the release of the rear wheel brake 6 at time t3.

[0050] By releasing switch 24, a supply voltage 34 can flow from the immobilizer control 12 to the motor 18, so that the motor 18 is actuated.

[0051] Fig. 2E shows the immobilizer arrangement 4 at a moment shortly after the immobilizer is released at time t4.

[0052] At this point, microcontroller 22 is still being kept operational by energy stored in capacitor 26. As soon as the energy stored in capacitor 26 is depleted, microcontroller 22 loses power and thus becomes inactive, causing the Fig. The initial state shown in 2A has been reached again. Reference symbol list 2 motor vehicles 4 Immobilizer arrangement 6 Rear wheel brake 8 brake caliper 10 motor units 12 Immobilizer control 14 User identification device 16 cases 18 engine 20 Brake control 22 microcontrollers 24 switches 26 Capacitor 28 two-core cable 30 Wake-up voltage 32 encoded signal 34 Supply voltage or diagnostic voltage

Claims

[1] Immobilizer arrangement (4) of a motor vehicle (2) comprising a parking brake (6) which can be electrically actuated by at least one motor (18), wherein the at least one motor (18) is controlled by a brake control (20), and an immobilizer control (12) arranged separately from the parking brake (6) for activating and deactivating the immobilizer of the motor vehicle (2), wherein the immobilizer control (12) is configured to receive authorization via a user identification device (14) and, upon successful authorization, to disable the immobilizer, wherein the parking brake (6) serves as the immobilizer, wherein the parking brake (6) and the immobilizer control (12) are connected to each other via a two-wire cable (28) to provide a supply voltage for the parking brake (6), wherein a microcontroller (22) for controlling the at least one motor (18) is provided in the parking brake (6),wherein the immobilizer control unit (12) is configured to modulate a coded signal (32) onto the supply voltage, wherein the microcontroller (22) is configured to check the coded signal (32) and to allow activation of the at least one motor (18) only after successful testing. [2] Immobilizer arrangement (4) according to claim 1, wherein the microcontroller (22) is arranged together with the motor (18) in a housing (16) of the parking brake (6). [3] Immobilizer arrangement (4) according to claim 1 or 2, wherein the microcontroller (22) is connected to an energy storage device, in particular a capacitor (26), for supplying energy to the microcontroller (22). [4] Immobilizer arrangement (4) according to one of the preceding claims, wherein the microcontroller (22) is connected to a switch (24), wherein the microcontroller (22) is configured to actuate the switch (24), wherein the switch (24) in a first position interrupts a current flow between brake control (20) and motor (18), wherein the switch (24) in a second position allows a current flow between brake control (20) and motor (18). [5] Motor vehicle with an immobilizer arrangement (4) according to any of the preceding claims. [6] Method for operating an immobilizer arrangement (4) according to any one of the preceding claims 1 to 4, wherein the immobilizer arrangement (4) is unlocked by a user identification device (14), wherein an immobilizer control unit (12) transmits a coded signal (32) via a two-wire cable (28) which provides a supply voltage for a parking brake (6) to a brake control unit (20) of the parking brake (6), wherein the coded signal (32) is modulated onto the supply voltage, wherein a microcontroller (22) in the brake control unit (20) checks the coded signal (32) and, if the check is successful, enables the control of a motor (18) of the parking brake (6) to release the parking brake (6). [7] Method according to claim 6, wherein a wake-up voltage (30) is provided by means of the immobilizer control (12) before transmission of the coded signal (32), so that the microcontroller (22) starts. [8] Method according to claim 6 or 7, wherein the microcontroller (22) charges an energy storage device, in particular a capacitor (26). [9] Method according to any one of claims 6 to 8, wherein the coded signal (32) is transmitted in the form of a voltage waveform or a PWM signal. [10] Method according to any one of claims 6 to 9, wherein the microcontroller (22) stores the coded signal (32) of the immobilizer control (12) upon initial startup.

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