Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2001-11-19
2004-05-04
Dolinar, Andrew M. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C324S433000
Reexamination Certificate
active
06732043
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of determining the starting ability of a starter battery of an internal combustion engine and a corresponding arrangement.
BACKGROUND INFORMATION
In a motor vehicle (or another system supplied with power primarily from an internal combustion engine), the functioning of the starter battery of the internal combustion engine is one of the most important prerequisites for ensuring good working order. An internal combustion engine is usually started by an electric starter which obtains electric power for the starting operation from a starter battery. The starter must briefly apply a torque capable of turning over the internal combustion engine at a certain minimum rpm. To do so, a sufficiently high current must be flowing through the starter, i.e., a sufficiently high voltage must be applied to it. If the starter battery is very cold, very old or partially discharged, the internal resistance of the battery may become so high that insufficient current and voltage are available to ensure starting. Such a problem is described in German Patent No. 197 05 634, for example.
For example, if the no-load voltage and the internal resistance of a starter battery are known, the starting ability of the starter battery for a given starting current and temperature can be checked. To this end, the terminal voltage can be calculated from known parameters and compared with the minimum voltage required to achieve the starting rpm. This is important, for example, to guarantee starting ability in start-stop systems in that the engine is started well in advance before reaching the starting limit in order to thereby recharge the battery through the generator.
Since the internal resistance of the starter battery also depends on the age of the battery in addition to its charge status and temperature, it must be determined again repeatedly at regular intervals. To obtain only the ohmic resistance of the electrodes and the electrolyte, which is crucial for the starting operation, one method is to calculate the internal resistance from the voltage dip and the maximum current in starting. However, the large current measurement range required for this purpose of up to 1 kA or more and the high current gradients of up to 1 kA/msec that occur are problematical in this regard. This makes high demands on the current sensors in a battery management system and under some circumstances results in the need for an additional sensor for this high current measurement range.
SUMMARY OF THE INVENTION
An object of the present invention is to find the simplest possible method of determining the starting ability of a starter battery without having to determine a starting current of the battery.
According to the present invention, it is now possible to determine the starting ability of a starter battery of an internal combustion engine without determining or calculating the starting current of the battery. Therefore, in the case of battery management systems which sense the battery current for determining the charge status, the current measurement range is greatly limited in comparison with traditional options, because it is possible according to the present invention to omit the determination of the charge drawn in starting, which is usually low.
The present invention utilizes, instead of the internal resistance and the starting current of the battery, the average voltage drop in the starter battery during starting to determine the starting ability. In this way, it is possible to eliminate complicated sensors for measuring the starting current.
According to a preferred embodiment of the method according to the present invention, the average voltage drop calculated according to the present invention is compared with a threshold value with the help of an equation of the form
U
0
(
soc, T
Batt
)−&Dgr;
U
Batt, mitt
(
soc, T
Batt
)=
U
Batt,min
where soc is the charge status of the starter battery, T
Batt
is the temperature of the battery, U
0
is the open-circuit voltage of the battery, &Dgr;U
Batt, mitt
is the average voltage drop in the battery during a starting phase and U
Batt, min
is the minimum voltage that can be used as a threshold value to achieve the starting rpm of the starter battery. It is usually possible to assume that minimum voltage U
Batt min
is known, charge status soc being supplied by the battery management system. On the basis of the known equation, it is also possible as an alternative to determine the minimum charge status for a successful start at a given starting temperature by solving the equation for soc.
According to another preferred embodiment of the method according to the present invention, the average voltage drop is calculated according to an equation
&Dgr;
U
Batt, mitt
(
soc, T
Batt
)−1
*&Sgr;(
U
0
(
soc, T
Batt
)−
U
Batt, i
)
i=
1
. . .n
at times i=1 . . . n during the turn-over phase of the starter motor. This yields an averaging, which permits the starting ability of a starter battery to be reliably estimated.
Open-circuit voltage U
0
of the battery at a known charge status is expediently determined according to an equation of the form
(
U
0
(
soc, T
Batt
)=6*(1.88+0,247
*soc+
(
T
BATT
−25)*0,23
e
−3)
at a known charge status and a known battery temperature and/or from the terminal voltage of the unloaded battery immediately before starting the internal combustion engine.
According to another preferred embodiment of the method according to the present invention, an engine characteristics map for the average voltage drop values is determined and stored as a function of the battery charge states and battery temperatures on the basis of average voltage drop values &Dgr;U
Batt, mitt
thus determined. Such an engine characteristics map makes is possible to determine the actual voltage drop values on the basis of the measurement or determination of the battery charge status and battery temperature through appropriate interpolation and extrapolation without having to perform specific calculations using the above equations.
REFERENCES:
patent: 6118252 (2000-09-01), Richter
patent: 6424157 (2002-07-01), Gollomp et al.
patent: 197 05 634 (1998-08-01), None
Dolinar Andrew M.
Kenyon & Kenyon
Robert & Bosch GmbH
LandOfFree
Method and arrangement for determining the starting ability... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and arrangement for determining the starting ability..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and arrangement for determining the starting ability... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3243101