Circuit device for a vehicle's electrical system and method

Abstract

Circuit device (100) for a vehicle electrical system, comprising - a bistable relay (104), with a switching input (114) and a switching output (116), with a first control input (108) for switching from a first switching state, in which the switching input (114) is electrically isolated from the switching output (116), to a second switching state, in which the switching input (114) is electrically coupled to the switching output (116), and a second control input (112) for switching from the second switching state to the first switching state, and - a number of monostable relays (118, 120) whose control input (124) is electrically connected to the switching output (116) of the bistable relay (104), so that the monostable relays (118, 120) follow the switching state of the bistable relay (104) as followers.

Description

Technical area

[0001] The present invention relates to a circuit device for an on-board network of a vehicle and a method for operating a circuit device in an on-board network of a vehicle. State of the art

[0002] Vehicle electrical systems supply a multitude of consumers with power. In conventional electrical systems, most functions can be disconnected from the battery via terminal relays. These terminal relays enable a condition-dependent supply to the electrical system and quiescent current management to protect the battery. An unauthorized drop in the terminal relays can have catastrophic consequences when supplying FUSI functions, as a large number of control units are immediately lost. When many control units (including non-FUSI control units) fail, the communication buses usually also fail, which can lead to a chain reaction. In conventional electrical systems, monostable, "normally off" relays are generally used. These drop out when the control signal is lost.There are numerous possible faults that can lead to the failure of conventional terminal relays, such as a short circuit on the supply line to the controlling body controller, a fuse failure of the controlling body controller due to aging, a power supply failure (LDO 12V -> 5V) in the body controller, a software hang-up in the control unit, a relay driver failure in the control unit, or a short circuit in the line to the relay. When the control voltage fails, the relay de-energizes and the power supply is interrupted.

[0003] With the electrification of functions, the number of consumers in the vehicle electrical system continues to grow. With the new features of highly automated driving, availability-relevant functions, such as autonomous lane keeping, are also being added. These functions must be implemented in a fail-operational manner, meaning that the function must continue to function even if an initial fault occurs. If the power supply to these functions via the vehicle electrical system is lost, this immediately leads to a violation of the safety goal of "controlled driving behavior."

[0004] One solution is to use bistable relays, which only change their switching state when a corresponding control signal is received and then remain in this switching state until the opposite control signal is received—usually at a separate control input. However, this solution is very expensive, and bistable relays also have a lower current-carrying capacity than monostable relays due to the lower contact force.

[0005] DE 10 2012 219 560 A1 discloses a vehicle with an internal combustion engine and with an on-board electrical system which comprises a battery, a power distributor, a starter, a generator and electrical consumers, such that the vehicle comprises a first supply line, the first supply line connects the power distributor to a starter terminal or to the starter, the vehicle comprises a second supply line, the second supply line connects the power distributor to a support point, and the electrical consumers and the generator are electrically connected to the support point.

[0006] DE 296 00 694 U1 describes an activation control circuit for car alarm systems, with a bistable relay element with an electrically actuated switching-off element (switch-off coil) and an electrically actuated switching-on element (switch-on coil) for switching the alarm system on or off, further with a switching-off stage and a switching-off stage for the switchable application of an operating voltage to the switching-off actuating element or the switching-on actuating element of the relay element, wherein the switching-off stage and the switching-on stage each have at least one signal input for applying a switching-off orSwitch-on control voltage or a corresponding voltage pulse for causing the switching element of the relevant switching stage to switch through, wherein the switch-on stage is connected in such a way that the supply voltage can only be effectively applied when the switch lock is in the zero position and the switch-off stage has a connection via which a control voltage is supplied from the electrical system of the vehicle when the ignition lock is actuated, at least in the radio position.

[0007] DE 28 27 305 A1 relates to a feedback device for the position of a switching device, with a bistable relay which is dependent on a switching element coupled to the switching device as a position transmitter and which has a first changeover switch which connects one of two display elements assigned to the positions of the switching device to a supply voltage, and with a monostable relay with a changeover switch whose changeover contacts are connected to supply voltages generating two different signals at the display elements and whose fixed contact is connected to the fixed contact of the first changeover switch associated with the bistable relay.

[0008] DE 20 2009 000 099 U1 describes a circuit arrangement with a battery coupler for providing predeterminable voltage and / or current variables from an electrical supply network for consumers or an input and at least one battery with programmable electronic circuit means for regulating and / or controlling the voltage and / or current variables as a function of target and / or actual data, wherein the circuit arrangement has a module with a plurality of separately switchable inputs and / or outputs, to which a different current carrying capacity can be assigned and the inputs and / or outputs for the consumers can be switched as a function of measured current, voltage and / or temperature values ​​in the circuit arrangement.

[0009] DE 10 2015 115 624 A1 discloses a power distributor for vehicles containing at least the following components: an electronics attachment and a central distribution module with a printed circuit board for electrical components and a feed-in busbar for connecting the printed circuit board to a feed-in connection and a cable directly connected to the power distributor. The electronics attachment is used to diagnose and, if necessary, switch the electrical components on the printed circuit board and is not located on the aforementioned printed circuit board, but can be connected to the printed circuit board via a plug-in contact. According to the invention, the advantages of the printed circuit board for distributing the signals to the various electrical components are combined with the advantages of a separate electronics attachment that is not connected to the cable or wiring harness from the outset.

[0010] None of the documents presented here shows a cost-effective solution for the state-dependent provision of FUSI functions. Description of the invention

[0011] An object of the invention is therefore to create a cost-effective alternative to the state-dependent supply of FUSI functions using the simplest possible means.

[0012] The object is achieved by the subject matter of the independent claims. Advantageous developments of the invention are specified in the dependent claims, the description, and the accompanying figures.

[0013] A circuit device according to the invention for an on-board electrical system of a vehicle comprises a bistable relay and a plurality of monostable relays, the respective control inputs of which are electrically connected to the switching output of the bistable relay. The bistable relay has a switching input, a switching output, a first control input, and a second control input. The first control input is configured to switch the bistable relay to a first switching state when a control signal is applied or received, by electrically isolating the switching input from the switching output. The second control input is configured to switch the bistable relay to a second switching state when a control signal is applied or received, in which the switching input is electrically coupled to the switching output. The monostable relays follow the switching state of the bistable relay as followers.

[0014] A relay is a switch that is activated by an electrical impulse. A monostable relay is either normally closed or normally open. When no control signal is applied, the relay falls into this standard position and remains in it. When a control signal is applied, the relay switches to the opposite position, i.e. a normally closed relay opens and a normally open relay closes. A monostable relay is a mechanical relay and its special design makes it extremely robust and durable. A monostable relay can last the lifetime of a vehicle, provided the number of switching cycles remains within the specification. A coil inside the relay generates a magnetic force to move the armature when an electric current flows through the relay.The armature has contacts for either opening or closing the respective circuit. The armature remains in the switched position as long as electrical current flows through the coil. When the power supply is interrupted, a spring or other mechanical component pushes the armature and contacts in the opposite direction. This predictably returns the relay to its original state in a monostable relay. A bistable relay remains in the position in which it was last energized. A bistable relay can have one or more coils.

[0015] Advantageously, the control inputs of the bistable relay are connected to a control unit. In a preferred embodiment, the control unit can be a body controller unit (BCU). This allows the circuit device to be controlled by a central control unit. In order to monitor the reliability of the circuit device, the switching state of the bistable relay can be monitored. For this purpose, the switching output of the bistable relay is connected to a diagnostic input, for example on the control unit. The diagnostic input can be a comparator or a comparator circuit. This makes it possible, for example, to monitor whether a voltage of approximately 12 V is present at the switching output of the bistable relay. This allows the voltage at the switching output to be compared with a threshold voltage of, for example, 11.4 V.

[0016] Furthermore, the number of monostable relays can be configured as normally open monostable relays. These can be monostable relays with a de-energized position as the stable position. Thus, when no control voltage is applied to the monostable relay, the circuit connected via it is open. This provides additional safety, as a failure of the body controller is intercepted via the bistable relay, but interference between the bistable relay and the monostable relay will result in a shutdown.

[0017] In a preferred embodiment, a number of loads with increased functional safety requirements are connected to the number of monostable relays and supplied via them. The monostable relays can thereby exploit their advantages in terms of current carrying capacity compared to the use of a comparable bistable relay.

[0018] Furthermore, loads can be connected to the bistable relay. If loads are originally only connected to the bistable relay and the load capacity of the bistable relay is insufficient, and if the number of control outputs of the body controller is insufficient, monostable relays are connected as "followers."

[0019] A method according to the invention for operating a circuit device in an on-board electrical system of a vehicle has at least one step of controlling a bistable relay and one step of switching a number of monostable relays. In the step of controlling the bistable relay, a first control input is used to switch from a first switching state in which a switching input of the bistable relay is electrically separated from a switching output of the bistable relay to a second switching state in which the switching input is electrically coupled to the switching output. In this case, a switching signal is applied to the first control input in the controlling step. Alternatively, in the step of controlling from the second switching state to the first switching state, another switching signal or the same switching signal is switched to the bistable relay via a second control input in order to switch the relay to the first switching state.In the step of switching the number of monostable relays, the monostable relays are controlled as followers of the bistable relay. For this purpose, the control inputs of the monostable relays are electrically connected to the switching output of the bistable relay. Short character description

[0020] An advantageous embodiment of the invention is explained below with reference to the accompanying figures. They show: Fig. 1 is a schematic representation of a circuit arrangement according to an embodiment of the present invention; and Fig. 2 a flowchart of a method according to an embodiment of the present invention.

[0021] The figures are merely schematic representations and serve only to illustrate the invention. Identical or equivalent elements are provided with the same reference numerals throughout. Detailed description

[0022] Fig. 1 shows a circuit device 100 for a vehicle's electrical system. A body controller 102 is configured to control a bistable relay 104. For this purpose, a control line 106 is connected to a first control input 108 of the bistable relay 104, and another control line 110 is connected to a second control input 112 of the bistable relay 104. The two control lines 106, 110 are coupled to control outputs of the body controller 102. A voltage of 12 V, for example, is applied to a switching input 114 of the bistable relay 104.

[0023] The bistable relay 104 is configured such that, in a first switching state, the switching input 114 is electrically separated from the switching output 116, and in a second switching state, the switching input 114 is electrically coupled to the switching output 116. Furthermore, the bistable relay 104 is configured such that, upon receiving a control signal via the first control input 108, the bistable relay 104 is switched from the first switching state to the second switching state, and upon receiving a control signal via the second control input 112, the bistable relay 104 is switched from the second switching state to the first switching state. Fig. 1 shows the bistable relay 104 in the first switching state, in which the switching input 114 is separated from the switching output 116.

[0024] The switching output 116 of the bistable relay 104 is coupled to a first monostable relay 118 and a second monostable relay 120 via a switching line 122 each. The two monostable relays 118, 120 are identical in the illustrated embodiment. They have a control input 124, a switching input 126, a switching output 128, and a ground connection 130. Thus, the switching output 116 of the bistable relay 104 is connected to the control input 124 of the monostable relays 118, 120. The ground connection 130 is connected to ground GND.

[0025] Furthermore, the switching output 116 of the bistable relay 104 is connected to a diagnostic input 134 of the body controller 102 via a diagnostic line 132. This allows the switching state of the circuit device 100 to be easily monitored. Since the monostable relays 118, 120 are configured as followers of the bistable relay 104, the monostable relays 118, 120 have the same switching state as the bistable relay 104, which is monitored by the body controller 102 via the diagnostic line 132 and the diagnostic input 134.

[0026] The one here in Fig. The body controller 102 shown in Figure 1 is a specific example of a control device in general. The monostable relays 118, 120 are normally open relays, meaning that the monostable relays 118, 120 have the de-energized position as their stable position.

[0027] The illustrated circuit arrangement 100 is particularly suitable for controlling loads that have increased requirements for functional safety.

[0028] The solution presented uses an intermediate bistable relay 104 to stably "store" the terminal state. If the body controller 102 fails as the control unit, the terminal state is retained. Only when the bistable relay 104 is actively deactivated by the body controller 102 is the terminal disconnected. Diagnostic coverage of the terminal state is achieved by reading back the terminal voltage.

[0029] In other words, Fig. 1 a body controller 102 that controls a bistable relay 104. The bistable relay 104 is controlled by current pulses with a length, typically <100 ms. A pulse on line 106 "relay on" switches the bistable relay to the "on" state. A pulse on line 110 "relay off" switches the relay to the "off" state. The relay state is maintained even if the controlling chain of action consisting of the body controller 102 and its circuitry fails.

[0030] Monostable relays 118 and 120 are now wired to act as followers to bistable relay 104. Monostable relays 118 and 120 are more cost-effective and generally have a higher current-carrying capacity than bistable relays. The switching state of the bistable relay is read back for diagnostic purposes. FUSI-relevant loads can now be supplied by both bistable relay 104 and the monostable follower relays 118 and 120. This increases the availability of the terminals in the vehicle.

[0031] Fig. Figure 2 shows a method for operating a circuit device 100 in a vehicle electrical system. For ease of understanding, the reference numerals for Fig.1 is retained as a reference. The method comprises a control step S1 and a further switching step S2. In control step S1, the bistable relay 104 is switched via a first control input 108 from a first switching state, in which a switching input 114 of the bistable relay 104 is electrically separated from a switching output 116 of the bistable relay 104, to a second switching state, in which the switching input 114 is electrically coupled to the switching output 116, or alternatively, via a second control input 112, from the second switching state to the first switching state. In step S2, a number of monostable relays 118, 120, which are configured as followers of the bistable relay 104, are switched according to the switching state of the bistable relay 104. For this purpose, the control inputs 124 of the monostable relays 118, 120 are electrically connected to the switching output 116 of the bistable relay 104.

[0032] Since the devices and methods described in detail above are exemplary embodiments, they can be modified widely by those skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the relative sizes of the individual elements are merely exemplary. LIST OF REFERENCE SYMBOLS 100 switching device 102 Body controller, control unit, body controller unit 104 bistable relay 106 Control line 108 first control input 110 additional control lines 112 second control input 114 Switching input 116 switching output 118 first monostable relay 120 second monostable relay 122 Switching line 124 Control input 126 switching input 128 switching output 132 Diagnostic line 134 Diagnostic input GND Ground S1 step of control S2 switching step

Claims

[1] Circuit device (100) for an on-board network of a vehicle, comprising - a bistable relay (104) having a switching input (114) and a switching output (116), having a first control input (108) for switching from a first switching state, in which the switching input (114) is electrically separated from the switching output (116), to a second switching state, in which the switching input (114) is electrically coupled to the switching output (116), and a second control input (112) for switching from the second switching state to the first switching state, and - a number of monostable relays (118, 120), the control input (124) of which is electrically connected to the switching output (116) of the bistable relay (104), so that the monostable relays (118, 120) follow the switching state of the bistable relay (104) as followers. [2] Circuit device (100) according to the preceding claim, in which the first control input (108) and the second control input (112) of the bistable relay (104) are connected to a control unit (102), in particular a body controller unit (BCU). [3] Circuit device (100) according to the preceding claim, wherein the switching output (116) of the bistable relay (104) is connected to a diagnostic input (134) of the control unit (102) in order to monitor a switching state of the circuit device (100). [4] Circuit device (100) according to one of the preceding claims, in which the number of monostable relays (118, 120) are designed with a de-energized position as a stable position. [5] Circuit device (100) according to one of the preceding claims, in which loads with an increased requirement for their functional safety are controlled by means of the number of monostable relays (118, 120). [6] Method for operating a circuit device (100) in an on-board network of a vehicle, comprising the following steps: a. controlling (S1) a bistable relay (104) via a first control input (108) for switching from a first switching state, in which a switching input (114) is electrically separated from a switching output (116), to a second switching state, in which the switching input (114) is electrically coupled to the switching output (116), or via a second control input (112) for switching from the second switching state to the first switching state, and b. Switching (S2) a number of monostable relays (118, 120) whose control input (124) is electrically connected to the switching output (116) of the bistable relay (104), wherein the monostable relays (118, 120) follow the switching state of the bistable relay (104) as followers.

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