Electricity: battery or capacitor charging or discharging – Battery or cell discharging – Regulated discharging
Reexamination Certificate
2002-03-06
2003-09-16
Toatley, Jr., Gregory J. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
Regulated discharging
C324S426000
Reexamination Certificate
active
06621250
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a battery capacity measuring and remaining capacity calculating system. More particularly, the present invention is concerned with a battery capacity measuring device for vehicle batteries, a remaining capacity calculating system for vehicle batteries, an automatic engine stopping/starting system for vehicles based on a remaining battery capacity, an electrical rotating machine control system for vehicles based on remaining battery capacity, and a fully-charged state judging system for vehicle batteries.
BACKGROUND ART
Background Art Relating to the First Mode of the Present Invention
A battery mounted in a vehicle is used as a power supply that supplies power to a starter for an engine and other accessories. The battery is charged from time to time by means of a generator that operates with power exerted by an internal combustion engine. A battery capacity measuring device measures a current battery capacity, and the generator is controlled based on the detected battery capacity.
For example, Japanese Unexamined Patent Application Publication No. 6-351166 discloses a technology for maintaining a battery capacity, which matches power consumption required by a load, with low fuel consumption, and preventing deterioration of a battery caused by overcharging or over-discharging. Herein, when a battery is nearly fully charged, an adjusting voltage is lowered for fear the battery may be overcharged. Nevertheless, generation must be able to be achieved with low fuel consumption. In contrast, when the battery capacity is insufficient, the adjusting voltage is raised for fear the battery may be over-discharged. In this example, the battery capacity is calculated based on an integrated value of charging/discharge current values of the battery detected by a current sensor.
In case a battery capacity is calculated based on an integrated value of charging/discharge current values of the battery, the precision in detection performed by a current sensor has a significant meaning. In particular, if a detected current value contains an error that must be offset, the offset values are integrated in order to calculate a current battery capacity. This makes it hard to properly control charging of the battery. The offset error is detected by measuring a current that flows when a circuit is open. As far as a vehicle is concerned, even when an engine is stopped, power is fed to accessories including a clock. It is therefore hard to measure the current with the circuit fully open. A method has been proposed in efforts to cope with this problem, wherein a dark current flowing with the engine stopped is estimated in advance, and an offset error is calculated with the dark current removed.
However, the dark current flowing with the engine stopped varies depending on the use state of an accessory or the type thereof. The dark current flowing with the engine stopped cannot always be estimated correctly. Thus, there is a fear that an error in a detected charging/discharge current may get larger.
According to the first mode of the present invention, the present invention attempts to solve the above problem underlying related arts. An object of the present invention is to provide a battery capacity measuring device capable of measuring a battery capacity with high precision.
Background Art Relating to the Second Mode of the Present Invention
A remaining capacity calculating system for calculating a remaining capacity that represents the charged state of a vehicle battery is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 10-319100. In this example, while a vehicle is running, a current flowing through a battery is measured in order to predict a change in the local concentration of electrolytic solution. The degree of polarization caused by the change in the concentration is then estimated. A remaining battery capacity is calculated using a representation of a voltage-current characteristic measured when the effect of polarization is limited.
However, the conventional remaining capacity calculating system cannot estimate the degree of polarization during, for example, running of a vehicle during which a battery is continuously charged. This poses a problem in that the remaining capacity of the battery cannot be calculated precisely when it is needed.
According to the second mode of the present invention, the present invention attempts to solve the foregoing problem underlying related arts. An object of the present invention is to provide a remaining capacity calculating system for vehicle batteries, an automatic engine stopping/starting system, and an electrical rotating machine control system. Herein, polarization occurring in a battery and adversely affecting the charged state of the battery that is a secondary battery is utilized effectively.
Background Art Relating to the Third Mode of the Present Invention
Fully-charged state judging systems for vehicle batteries include a system that monitors a rise in the voltage at the terminals of a battery (for example, a lead-acid battery) to judge whether a battery is fully charged. This device utilizes a phenomenon that as long as a battery is charged with a constant current, when the battery is nearly fully charged, the voltage at the terminals of the battery rises.
However, when a vehicle is running, polarization attributable to a change in a charging/discharge current or a change in the concentration of electrolytic solution, occurs in a battery. Moreover, an output voltage of an alternator is regulated by a regulator and provided as an adjusting voltage. Therefore, a rise in the voltage at the terminals of the battery is not always associated with the fact that the battery is fully charged. This poses a problem in that even when the voltage at the terminals of a battery is monitored, it may not be able to judge highly precisely whether the battery is fully charged.
According to the third mode of the present invention, the present invention attempts to solve the above problem underlying related arts. An object of the present invention is to provide a fully-charged state judging system for vehicle batteries and a remaining battery capacity calculating system employing the fully-charged state judging system. The fully-charged state judging system can highly precisely judge whether a battery is fully charged, irrespective of an adjusting voltage produced by a regulator or polarization occurring in a battery.
DISCLOSURE OF INVENTION
In the aspect of the present invention set forth in claim
1
, a microcomputer (
80
) includes a fully-charged state judging means.(
80
e
), a detected current integrating means (
80
a
), a dividing means (
80
b
), and a correcting means (
80
c
). The fully-charged state judging means detects whether a battery is fully charged. The detected current integrating means integrates the current values that are detected by a current sensor during a period from the instant a battery is fully charged to the instant it is fully charged thereafter. The dividing means divides an integrated value of detected current values provided by the detected current integrating means by, the length of the period. The correcting means corrects a detected current with an offset using a quotient provided by the dividing means.
Owing to the above features, when a battery is fully charged, a battery capacity that shall be denoted by SOC (state of charge) is restored to 100% that is identical to a battery capacity attained when the battery is fully charged previously. During a period from the instant a battery is fully charged previously to the instant it is fully charged this time, the battery is discharged and charged by the same amount of current. Therefore, an integrated value calculated by integrating the current values that are detected during the period from the instant a battery is fully charged previously to the instant it is fully charged this time contains offset values that are caused by the current sensor. The integrated value of the detected current values is divided
Ito Shin'ichi
Kawai Toshiyuki
Kikuchi Katsuhide
Kikuchi Tetsuro
Kishida Shinji
Toatley , Jr. Gregory J.
Toyota Jidosha & Kabushiki Kaisha
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