Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-03-09
2003-12-09
Hoff, Marc S. (Department: 2847)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S064000, C307S010100, C701S029000
Reexamination Certificate
active
06662123
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent document 100 11 404.0, filed Mar. 9, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a device for identification of an external power supply in a vehicle, and particularly for identifying external starting of a motor vehicle which has an electrical on-board power supply system with a battery for providing an on-board power supply system voltage. In addition, the invention relates to a method for operation of such a device.
Safety-relevant functions in vehicles, such as for example the very recently developed electric brake, are increasingly being separately electrically powered. In order to assure the functionality of such components at all times, they must receive an uninterrupted supply of electrical power. For this purpose, in vehicles it is known to provide two energy sources, namely a battery and a generator.
Since the life of a conventional lead-acid battery is generally shorter than the life of the vehicle, situations regularly arise in which only one of the two energy sources can still operate. In most cases, the generator will have a longer life than the battery in this arrangement.
One method for monitoring the serviceability of a battery by means of its battery voltage is disclosed in German patent document DE 195 17 709. The result of the monitoring and the data determined in the process are in this case used, in particular, to decide whether a machine which is connected to the battery will or will not be allowed to operate further.
If the generator is damaged or overloaded when the battery is discharged or defective, the supply to the loads is then no longer ensured and the vehicle can enter a safety-critical state. The generator can be overloaded when more loads are connected than it can nominally supply. For this reason, emergency measures must be taken which, firstly, warn the driver and, secondly, also keep the on-board power supply system in an operationally safe state for as long as possible. The latter can be achieved by retaining only a few important loads in a switched on or connected state.
Furthermore, when the battery is discharged or defective, the vehicle can no longer be started. Thus, starting capability may be regarded as a criterion for the state of the battery energy source. However, in situations such as this, a second vehicle is often used as a starting aid, simulating, so to speak, an intact battery. In this situation, the safety measures mentioned above are not carried out and the warning or stabilization measures do not come into play. For this reason, external starting must be identified.
All that is known in this context from German patent document DE 196 49 392 C2 is to provide a connecting cable for voltage maintenance to be supplied by an external power source having an electronic circuit, which checks that the cable has been connected correctly. In German patent document DE 298 06 441, a warning lamp is provided to indicate that an additional or external energy storage unit has been connected to the vehicle on-board power supply system.
One object of the invention is thus to provide a method and apparatus of the type described initially, which can detect the connection of an external power supply and the performance of external starting, as reliably as possible.
Another object of the invention is to provide such a device and a corresponding method, which can be produced easily and cost-effectively.
These and other objects and advantages are achieved by the method and apparatus according to the invention, in which a monitoring unit is arranged between the battery and the on-board power supply system, and includes a sensor for detection or monitoring of the on-board power supply system voltage, or interacts with such a sensor. The invention is based, in particular, on the proposition that a change in the on-board power supply system voltage and/or in the battery parameters occurs when electrical contact is made between an external battery and a vehicle battery. According to the invention, this change is detected and is evaluated as a function of various parameters relating to external starting. In contrast to the abovementioned prior art, the on-board power supply system voltage is used, in particular, rather than the battery voltage, as the output variable for assessment.
In addition, it is possible to provide the monitoring unit with a sensor for detection of the electric current flowing out of the battery and/or the electric current flowing into the on-board power supply system, or to interact with such a sensor. Together with the detected on-board power supply system voltage, this also allows changes in the on-board power supply system load to be recognized and, advantageously, to be taken into account in the evaluation.
It is also possible to provide the monitoring unit with a sensor for detecting the operating temperature of the battery, or to interact with such a sensor. In principle, the connection of two batteries electrically represents a parallel circuit, as a result of which the total internal resistance of the batteries is reduced. The internal resistance can in this case be measured by a current and voltage measurement using the said sensors. The reduced internal resistance also results in an increase in the current flowing through the battery, which is also associated with a measurable increase in the battery temperature.
This evaluation process can be automated by providing the monitoring unit with a computer unit, in particular a microcontroller, for determination of changes in the electrical on-board power supply system variables.
Any change in the on-board power supply system load can advantageously be recognized by a controllable switch which interacts with the microcontroller, or alternatively by means of vehicle data which are provided via a vehicle CAN bus and are transmitted to the microcontroller.
A further embodiment envisages a timer for detection of a time duration (particularly a minimum duration) of any drop in voltage which may occur in the on-board power supply system voltage. Together with recognition that the monitoring unit is being started or restarted after a power-on reset, the timer makes it possible to detect a total loss of battery voltage, in order to distinguish between this and brief drops in voltage.
It is furthermore possible to provide for the monitoring unit to enter a sleep mode after a time interval which can be predetermined, thereby saving energy for supplying the unit. In this case, means can be provided for storing an on-board power supply system voltage value (particularly a read-only memory), and means can be provided for comparing the stored value with an approximately sensed present on-board power supply system voltage. When the on-board power supply system voltage is in a stable state, then, once the monitoring unit has been “awakened”, only minor changes can occur, in principle, in the voltage, compared with the stored value.
The method according to the invention, for operating the above-mentioned device in a motor vehicle having an electrical voltage generator operated by an engine, includes in particular, the following:
a) monitoring at least one of the electrical on-board power supply system variables and/or the state of the monitoring unit during a starting phase of the monitoring unit;
b) monitoring at least one of the electrical on-board power supply system variables before starting the engine; and
c) monitoring at least one of the battery state variables during an engine starting phase.
In the method, an additional step d) can now be provided by monitoring at least one of the battery state variables once the engine has been successfully started until the vehicle starts to be driven, in order to detect whether the disconnection of an external starting cable is identified. Specifically, according to the invention, after an external start has been carried out by means of an electrical starting jumper cable, the starting jumper
Kneifel Marcus
Maeckel Rainer
Crowell & Moring LLP
Daimler-Chrysler AG
Kim Paul L.
LandOfFree
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