Electricity: battery or capacitor charging or discharging – Battery or cell charging – With thermal condition detection
Reexamination Certificate
2000-03-16
2001-03-20
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
With thermal condition detection
Reexamination Certificate
active
06204640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Filed of the Invention
The present invention relates to a battery charger and a battery charging method for charging a battery and particularly relates to a battery charger and a battery charging method suited for charging a battery, such as a nickel metal hydride battery, which emits high heat while being charged.
2. Discussion of the Prior Art
Presently, a chargeable battery which can be repeatedly used for the power supply of, for example, a power tool is used.
A nickel cadmium battery is popular as a battery for the power tool, and a battery charger for quickly charging the battery by applying high current thereto is used. Specifically, the battery is quickly charged in about 20 minutes and a power tool can be continuously used by switching a battery to that which has been charged.
The inventor of the present invention studied improving the performance of a power tool by using a nickel metal hydride battery as a battery therefor. Although the nickel metal hydride battery can increase a capacity compared to a nickel cadmium battery, it generates high heat while being charged. If the temperature of the battery becomes high by the generated heat, the electrodes and separators of the cells within the battery deteriorate and battery life is shortened. Due to this, it is impossible to quickly charge the nickel metal hydride battery with high current as done for the nickel cadmium battery stated above.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-stated problems and an object of this invention is to provide a battery charger and a battery charging method capable of appropriately charging a battery in a short time while suppressing the temperature rise of the battery which is being suppressed.
In order to accomplish the said object, a battery charger according to the present invention characterized by comprising:
a temperature detecting section for detecting a present battery temperature;
a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;
a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section is constant; and
a charge control section for charging a battery with the current value retrieved by said current value retrieving section.
In order to accomplish the said object, a battery charger according to the present invention characterized by comprising:
a storage device storing a target temperature value which a battery temperature is intended to reach;
a temperature detecting section for detecting a present battery temperature;
a temperature gradient calculating section for calculating a temperature rise gradient from charging time based on a difference between a battery temperature at the beginning of battery charge and said target temperature value held by said storage device;
a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;
a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise gradient; and
a charge control section for charging the battery with the current value retrieved by said current value retrieving section.
In order to accomplish the said object, a battery charger according to the present invention characterized by comprising:
a storage device storing a target temperature value which a battery is intended to reach;
a temperature detecting section for detecting a present battery temperature;
a temperature rise pattern retrieving section for retrieving a temperature rise pattern for completing battery charge at said target temperature value based on a difference between a battery temperature at the beginning of the battery charge and said target temperature value held by said storage device;
a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;
a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise pattern; and
a charge control section for charging the battery with the current value retrieved by said current value retrieving section.
In accordance with the more preferred teaching of the present invention, said temperature rise pattern is such that the temperature rise value is relatively high in a first half of battery charge and is relatively low in a second half of battery charge.
In accordance with the more preferred teaching of the present invention, said temperature rise pattern is approximated polygonally.
In accordance with the more preferred teaching of the present invention, said target temperature value is a value for completing the battery charge at the lowest temperature.
A battery charging method for making a battery side hold information on a target temperature value, which a battery is intended to reach, corresponding to charging time and charging the battery by means of a battery charger in accordance with the target temperature value, according to the present invention characterized in that said battery charger comprises:
a storage device storing a temperature rise pattern for completing battery charge at the target temperature value read out from the battery side;
a temperature detecting section for detecting a present battery temperature;
a temperature rise pattern retrieving section for retrieving a temperature rise pattern from said storage device based on a battery temperature at the beginning of the battery charge and charging time;
a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;
a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise pattern; and
a charge control section for charging the battery with the current value retrieved by said current value retrieving section.
In accordance with the more preferred teaching of the present invention, said target temperature value is a value for completing the battery charge at the lowest temperature.
A battery is charged while adjusting a current value so that a temperature rise value may be constant. This makes it possible to charge the battery so that a battery temperature at the time of the completion of charge becomes a predetermined value. It is, therefore, possible to charge a nickel metal hydride battery or the like which has large temperature increase in a short time without increasing the battery temperature.
A temperature rise pattern is retrieved from charging time based on the difference between a battery temperature at the beginning of battery charge and a target temperature value which the battery is intended to reach and which is held by a storage device. The battery is then charged while adjusting a current value so that a temperature rise value may become the temperature rise pattern. Due to this, by optimizing the temperature rise pattern, it is possible to charge the battery so that a battery temperature at the time of the completion of charge may become a predetermined value. It is, therefore, possible to charge a nickel metal hydride battery or the like, which has large temperature increase, in a short time without increasing the battery temperature.
A temperature rise pattern is retrieved from charging time based on the difference between a battery temperature at the beginning of battery charge and a target temperature value which a battery is intended to reach and which is held by a storage device. The battery is then charged while adjusting a current value so that a temperature rise value may become th
Makita Corporation
Tolpin Thomas W.
Tso Edward H.
Welsh & Katz Ltd.
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