DE102008010979A1 - On board supply system for motor vehicle, has control unit arranged to control switches within sub-networks to influence voltage supply of sub-networks and to transmit condition of sub-networks to control device outside networks - Google Patents

Abstract

The supply system (1) has sub-networks (3) comprising electronic controllable switches (31, 32) for switching and switching off of voltage sources within the sub-networks. An electrical control unit (33) and a safety relevant load (34) are supplied with operating voltage. The electrical control unit is arranged to control the switches within the sub-networks to influence voltage supply of the sub-networks and to transmit the condition of the sub-networks to a control device (11) outside the sub-networks.

Description

The Invention relates to a vehicle electrical system for a motor vehicle, in particular an electrical system with several separate subnets.

State of the art

Around supply a vehicle electrical system with electrical energy, Nowadays, an engine is usually used by an internal combustion engine a V-belt driven alternator used, which a predetermined by a manipulated variable target voltage generated. The manipulated variable is controlled by a voltage regulator delivered, which has the task by means of the manipulated variable over the output voltage of the generator, the vehicle electrical system voltage independently of load and speed of the internal combustion engine in a given Keep area constant. If there is a failure in the voltage generation or comes to a short circuit in the electrical system, the power supply can of the vehicle electrical system collapse, and the consumers connected to it are cancelled.

In Modern motor vehicles are becoming more and more safety-relevant Consumers integrated into the electrical system, such as electronic Steering or braking systems. These must not fail, while the vehicle is driving, or they must in the case of a fault of the electrical system at least as long remain functional, that the vehicle safely to a stop can be brought.

Therefor a structure is provided for in newer on-board network architectures, in the safety-related consumer and associated monitoring devices are connected to one or more separate subnets, wherein each subnetwork via a base on-board network of one arranged there Generator is powered. The subnet is usually through disconnected a voltage transformer from the base board network and includes a separate energy storage, allowing consumers in this subnet supplied with high voltage quality and high reliability can be. The monitor in the Subnetwork has the task of doing the proper Function of the safety-relevant consumer and / or the subnetwork to monitor and in case of failure to cause a Driver of the vehicle the error is reported.

If only the power supply in the subnet fails due to a fault, for example, by a short circuit in the subnet, and the base board network yet is functional, so the vehicle can continue to drive However, due to the failure in the subnet, consumers are and also the monitor is no longer functional, so that a targeted feedback on the functional failure to the driver is not possible.

From the publication DE 10 2005 004 330 A1 an on-board network for security-relevant consumers is known, which has a base-board network and a sub-network of the type described above, wherein the sub-network can be supplied with energy via different supply paths and has switches for separating the supply routes. In the electrical system, a control device is present, which controls the switch depending on malfunctions in the electrical system and thus prevents a spread of errors within the electrical system, primarily the spread of a fault from the base vehicle network to the subnet. In this case, however, it is not disclosed how it is ensured that the control device itself is still supplied with energy in order to still be able to control the switches if the error situation and a power failure connected thereto have already occurred.

Next describes the published patent application DE 102 51 589 A1 a vehicle network structured in two subnetworks, in which a safety-relevant consumer is supplied with energy via two redundant supply paths from both subnetworks. The supply paths can be selected via switches which are controlled by a switching control unit. Also in this document, the design of the switching control unit is not disclosed, so that their arrangement within the subnets and their energy supply is unclear.

moreover Both publications leave the problem unresolved, in case of failure of a subnet, a corresponding message to trigger the driver of the motor vehicle, so that this - too in case of a failure and temporary still working security relevant consumer - so appropriate arrangements to remedy the situation as soon as possible Can meet problems.

Advantages of the invention

By the present invention is incorporated in at least two separate subnetworks subdivided vehicle electrical system for a motor vehicle, in which a control unit in one of the subnets also after Occurrence of a fault in the subnet reliable in the Able to propagate the fault on the rest of the electrical system prevent and notify a driver of the motor vehicle to enable.

These advantages are achieved by having in a vehicle electrical system for a motor vehicle with at least two to be supplied with electrical energy subnetworks, wherein at least a first subnetwork electronically controllable switching elements to the supply and from comprises power sources within the subnet and is arranged to supply at least two electrical loads with operating voltage, of which a first load is set up to be supplied with operating voltage from at least one second subnet, the first load is a control unit which is set up, to control the switching elements within the subnet to affect the power supply of the subnet and which is adapted to transmit a state of the subnet to a controller outside the subnet. When an error occurs within the first subnetwork, the control unit of the first subnetwork can selectively prevent the propagation of the error to another subnetwork by a suitable control of the switching elements, so that the first subnetwork can optionally be isolated and switched off. The fact that the control unit is still functional due to the additional power supply from a second subnet, it can be ensured that the state of the first subnetwork can be transmitted even after the shutdown of the first subnet to a higher-level control unit of the electrical system, so that the control unit a Notify the driver.

Across from an integration of the control unit in a central control unit of the electrical system has the arrangement of the control unit in the subnet the advantage that in differently structured on-board networks with different Consumers in several subnets only the subnet modular must be integrated into the electrical system and the central control unit not separately adapted to the conditions of the on-board network structure must become.

In A first advantageous embodiment of the invention is the second Subnet a baseboard network that is set up at least to feed the first subnet with electrical energy. Thus, can the control unit through the base board network redundant with operating voltage be supplied and can fulfill their tasks reliably, as long as the base board network is functional.

In a further advantageous embodiment of the invention are first and the second subnet set up, parallel to each other to be powered by a base board network with electrical energy. In this structure, the electrical system is in a baseboard network and two subnetworks subdivided, the subnets preferably fail-safe are executed and assumed that not both subnets fail at the same time. The control unit of the first subnetwork can then supply either from the first or the second subnet with operating voltage be able to continue operating in the event of a failure of one of the subnets to stay.

In each of the embodiments of the invention, it is advantageous here, if the control unit comprises means which are set up, those subnetworks which supply the control unit with voltage, decouple stress technology. This can be reliable prevents a fault in the subnet over continues the control unit on the rest of the electrical system and there leads to further failures.

Especially if a second consumer of at least the first subnetwork safety-relevant consumer, there are special benefits by the invention. For safety-relevant consumers It is especially important that the control unit perform their functions even after an error in the subnet can and the state of the subnet and thus an imminent Failure of the safety-relevant consumer to the central control unit pass on and so for an error message to the driver can provide.

Further Features and advantages of the invention will become apparent from the following Description of embodiments with reference on the attached figures. Show it:

1 a schematic representation of a vehicle electrical system for a motor vehicle in a first embodiment of the present invention;

2 the schematic representation of an alternative embodiment of the invention; and

3 the schematic representation of another embodiment of the invention.

1 provides the schematic structure of a vehicle electrical system 1 for a motor vehicle. In the electrical system 1 includes a baseboard network 2 a generator 21 , which generates a voltage necessary for the power supply of the vehicle electrical system and is driven by a V-belt by a drive internal combustion engine of the motor vehicle, a battery 22 , a starter 23 for starting the internal combustion engine, which in the usual way via a switch with the base board network 2 connected, and a consumer 24 passing through a fuse 25 with the base board network 2 connected is. The consumer 24 is hereby representative of a plurality of consumers who are not safety relevant in the sense that their failure interferes with the driver's direct control of the vehicle, such as lights, wipers, power windows, heaters, etc.

The electrical system 1 includes next to the base board network 2 a subnet 3 , which has a voltage transformer 30 and a fuse 26 to the Ba sisbordnetz 2 connected. In the subnet 3 is a control unit 33 arranged, which is capable of the voltage technical condition of the subnetwork 3 to judge and to recognize a mistake.

In addition, it can be provided that the control unit 33 Functions one also to the subnet 3 connected consumer 34 controls. The consumer 34 is in the embodiment described here a safety-relevant consumer, such as an electronic brake circuit.

In order for increased reliability of the subnet 3 is also an auxiliary battery 35 provided which the subnetwork 3 additionally supplied with energy at peak demand or after a separation of the subnetwork 3 from the base board network 2 at least for a short time is still able to provide energy for the subnet 3 to provide. The auxiliary battery 35 is over a switch 31 to the subnet 3 connected by the control unit 33 is controlled. During a normal error-free driving operation of the motor vehicle is the switch 31 closed, leaving the auxiliary battery 35 can be loaded automatically when needed.

In the subnet 3 is another switch 32 provided to the voltage transformer 30 with the subnet 3 to connect or from the subnet 3 to separate. Also the switch 32 is through the control unit 33 controlled and is also closed during normal driving.

The control unit 33 is in addition to the voltage connection to the subnet 3 via another supply line with the base on-board network 2 connected, being between baseline network 2 and control unit 33 a fuse 27 is arranged.

In addition, the control unit 33 via a data connection 12 with a control unit 11 of the electrical system 1 connected, on the one hand, the state of the subnetwork 3 to the control unit 11 and commands to control the consumer 34 from the control unit 11 to recieve. The data connection 12 is preferably designed as a bus system through which the control unit 11 even with other devices of the electrical system 1 is connected to control the devices or to receive from these status messages. Because the data connections between the control unit 11 and those devices are irrelevant to the present invention, they are in 1 and the following figures omitted for clarity.

Now occurs a short circuit in the voltage converter 30 on, so this is through the control unit 33 then the switch 32 opens, leaving the subnet 3 is separated from the error and the consumer 34 at least for a short while by the auxiliary battery 35 can still be supplied with energy and fulfill its function. Also the control unit 33 will be out of the subnet at this time 3 supplied with operating voltage. The control unit 33 sends a corresponding status message to the control unit 11 of the electrical system 1 so the controller 1 a first warning about the error and an impending failure of the subnet 3 can output to a driver of the motor vehicle.

If now in a continuous operation of the motor vehicle, the voltage of the auxiliary battery 35 falls below a critical value, opens the control unit 33 also the switch 31 , disconnects the auxiliary battery 35 from the subnet 3 and thus switches the subnet 3 to prevent further damage. After the shutdown of the subnet 3 becomes the control unit 33 over the base board network 2 supplied with operating voltage, so that the control unit 33 continue the state of the subnet 3 to the control unit 11 of the electrical system 1 can report and it so the control unit 11 it is possible to issue further error messages to the driver.

If a short circuit is not in the voltage transformer 30 but within the lines of the subnet 3 occurs, then opens the control unit 33 immediately both switches 31 . 32 to the subnet 3 shut down and a potential fire hazard largely excluded. Even in such a case, the control unit 33 from the base board network 2 supplied with operating voltage and can continue to send status messages to the control unit 11 to transfer.

To a coupling of errors from the subnet 3 to prevent in the electrical system, instructs the control unit 33 appropriate means to decouple the two networks. Possible overvoltage or overcurrent protection measures are suitably realized by diodes and / or other switching elements or fault current fuses. Also a spatial separation of the connections and supply circuits in the control unit 33 may be appropriate to provide sufficient decoupling.

An alternative embodiment of a vehicle electrical system according to the invention 1 is in 2 shown.

Here includes the electrical system 1 next to the first subnet 3 another subnet 4 , which is analogous to the subnetwork 3 is structured and also a control unit 43 , a security-relevant consumer 44 and an auxiliary battery 45 having.

The subnet 4 is also due to a voltage transformer 40 and about a backup 28 with the base board network 2 connected. The voltage converter 40 can through a switch 42 from subnet 4 be disconnected, and the auxiliary battery 45 can through a switch 41 from the subnet 4 be separated. The control unit 44 is analogous to the control unit 43 capable of the switches 41 and 42 according to an existing error situation in the subnet 4 to isolate the error.

Instead of a redundant supply route to the base board network 2 are the control units 33 and 43 for supply with operating voltage additionally with in each case the other subnetwork 4 and 3 connected, so that in case of failure of the subnet 3 the control unit 33 through the subnet 4 is supplied with operating voltage, and in case of failure of the subnet 4 the control unit 43 from the subnet 3 is supplied. Because it is the subnets 3 and 4 are subnets, which are realized with high reliability, for example, to supply two separate electronic brake circuits as a consumer 34 and 44 with energy, it can be assumed that at least one of the subnets 3 or 4 has a corresponding desired voltage as long as the motor vehicle is not stopped due to further errors anyway.

The representation in 3 shows a further alternative embodiment of a vehicle electrical system 1 according to the invention, in which in the subnet 4 opposite the subnet 3 an increased need for supervision by the control unit 43 consists.

The subnet 3 in this embodiment is analogous to the first, in 1 shown structure of the electrical system 1 with the base board network 2 connected. Similarly, the subnet is parallel to this 4 analogous to the base board network 2 connected, the control unit 43 for additional supply with operating voltage also with the base board network 2 is connected and in this supply line a fuse 29 is interposed.

To an even more fail-safe supply of the control unit 43 In addition, this is in addition to the subnet 3 connected, so the control unit 43 even with a simultaneous failure of two supplying subnets still operational.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005004330 A1 [0006]
• - DE 10251589 A1 [0007]

Claims (5)

Electrical system ( 1 ) for a motor vehicle having at least two subnetworks to be supplied with electrical energy ( 2 . 3 . 4 ), wherein at least a first subnetwork ( 3 . 4 ) electronically controllable switching elements ( 31 . 32 . 41 . 42 ) for connecting and disconnecting voltage sources within the subnetwork ( 3 . 4 ) and at least two electrical consumers ( 33 . 34 . 43 . 44 ) are to be supplied with operating voltage, of which a first consumer ( 33 . 43 ) is composed of at least a second subnetwork ( 2 . 3 . 4 ) to be supplied with operating voltage, characterized in that the first consumer ( 33 . 43 ), the switching elements ( 31 . 32 . 41 . 42 ) within the subnetwork ( 3 . 4 ) to control the power supply of the subnet ( 3 . 4 ), and is set up, a state of the subnet ( 3 . 4 ) to a control unit ( 11 ) outside the subnet ( 3 . 4 ). Electrical system ( 1 ) according to claim 1, characterized in that the second subnetwork ( 2 ) is a base board network, which is set up, at least the first subnetwork ( 3 . 4 ) to feed with electrical energy. Electrical system ( 1 ) according to claim 1, characterized in that the first and the second part network ( 3 . 4 ) are arranged parallel to one another from a base on-board network ( 2 ) to be fed with electrical energy. Electrical system ( 1 ) according to one of the preceding claims, characterized in that the first consumer ( 33 . 43 ) Means for voltage decoupling of the first consumer ( 33 . 43 ) comprises subnetworks supplying voltage. Electrical system ( 1 ) according to one of the preceding claims, characterized in that a second consumer ( 34 . 44 ) of at least the first subnetwork ( 3 . 4 ) is a safety-relevant consumer.