Electricity: battery or capacitor charging or discharging – Means to identify cell or battery type
Reexamination Certificate
1999-03-18
2001-05-08
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Means to identify cell or battery type
C320S114000
Reexamination Certificate
active
06229280
ABSTRACT:
This application claims priority to Japanese Patent Application No. 10-68685, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to battery-charging systems for electrical equipment. More particularly, the present invention relates to a battery-charging system that includes an electric power tool operating on rechargeable internal batteries and a battery charger for charging the internal batteries of the electric power tool.
2. Description of the Related Art
One type of conventional rechargeable electric power tool incorporates a detachable battery pack mounted in the lower end of the handle thereof. When the battery pack needs to be recharged, it is detached from the handle of the tool and set on a separate charger. After the charging is completed, the battery pack is mounted back in the handle to resume operation. If an electric power tool operating on a detachable battery pack is used for extended periods, for example, on a production or assembly line of an automobile plant, an auxiliary battery pack is set in a charger for recharging. When the pack mounted in the tool is discharged, the operator replaces it with the one recharged by the charger and sets the discharged battery pack on the charger for recharging.
Battery packs used for the above-described purpose are generally designed to maximize their capacity and thus the operating time of the tool. This tends to increase the size and weight of the packs, which in turn places an excessive physical strain on the operators and reduces the operability of the tools and work efficiency. This tendency is particularly pronounced when such large and heavy battery packs are used on assembly lines for an extended period; the operability of the tools may be severely affected so as to significantly reduce the productivity of the plant. In addition, loss of time by replacing discharged battery packs has been a significant factor that reduces work efficiency.
Furthermore, when bolts and screws must be tightened to specific torque, electric power tools of the above-described type often fail to fulfill the task, as the operators cannot ascertain the charge level of the battery packs.
Chargers used for such battery packs continue to supply charging current even after the battery packs are fully charged, therefore placing the batteries or cells in the pack under heavy load and reducing the charge efficiency.
SUMMARY OF THE INVENTION
In view of the above-identified problems, an important object of the present invention is to provide a battery-charging system that improves the work efficiency and the operability of electric power tool included in the system.
Another object of the present invention is to provide a battery-charging system that allows the charge level of the batteries to be externally monitored.
Still another object of the present invention is to provide a battery-charging system that controls charging according to the charge/discharge level of the batteries so as to lessen the load on the batteries.
Yet another object of the present invention is to provide a battery-charging system that can easily measure the temperature of the batteries so as to control charging in accordance with the measured temperature of the batteries, thereby lessening the load on the batteries.
The above objects and other related objects are realized by the invention, which provides a power tool charging system including an electric power tool and a charger on which the tool is set for charging. The electric power tool includes at least one rechargeable battery on which the electric power tool operates, a controller for monitoring charge/discharge level of the at least one battery and for generating data on the charge/discharge level of the at least one battery, and a data transmission terminal for externally providing the data on the charge/discharge level of the at least one battery. The electric power tool is set on the charger for charging the at least one battery. The charger can supply charging current to the at least one battery when the electric power tool is set on the charger.
According to one aspect of the present invention, the charger further includes a data receive terminal which is connected to the data transmission terminal of the electric power tool when the electric power tool is set on the charger. The data receive terminal receives the data on the charge/discharge level of the at least one battery from the controller and changes the amount of the charging current based on the charge/discharge level data.
According to another aspect of the present invention, the charger further includes an indicator for indicating the remaining charge of the at least one battery based on the charge/discharge level data received from the controller.
According to still another aspect of the present invention, the electric power tool further includes a temperature sensor for measuring and generating data on the temperature of the at least one battery and a temperature transmission terminal for externally providing the data on the measured battery temperature.
According to yet another aspect of the present invention, the charger further includes a temperature receive terminal which is connected to the temperature transmission terminal when the electric power tool is set on the charger. The charger is adapted to read the battery temperature and change the amount of the charging current based on the battery temperature.
In accordance with another aspect of the present invention, the amount of the charging current is changed to zero amperes.
In one practice, the charger increases the amperage of the charging current to the level prior to the decrease to zero amperes once the temperature of the at least one batteries decreases to a predetermined level.
In another practice, the electric power tool is determined to have been set on the charger for charging when the charger can read the battery temperature by receiving data on the battery temperature at the temperature receive terminal.
To carry out the invention in one preferred mode, the charger further includes a pair of first charge terminals for supplying the charging current to the at least one battery and the electric power tool further includes a pair of second charge terminals that are connected to the at least one battery and that establish contact with the first charge terminals when the electric power tool is set on the charger. In addition, when the voltage between the second charge terminals exceeds a predetermined first threshold, the at least one battery is determined to be fully charged. In this case, the charging current is shut off. When the voltage between the second charge terminals is no higher than a predetermined second threshold, the at least one battery is judged defective, thus also shutting off the charging current.
In one practice, the terminals of the electric power tool are provided thereon in proximity to one another, and the terminals of the charger are provided thereon in proximity to one another so as to establish electrical contact with the corresponding terminals of the electric power tool when the tool is set on the charger for charging the at least one battery.
Other general and more specific objects of the invention will in part be obvious and will in part be evident from the drawing and description which follow.
REFERENCES:
patent: 5298346 (1994-03-01), Gyenes
patent: 5463305 (1995-10-01), Koenck
patent: 5572110 (1996-11-01), Dunstan
patent: 5606242 (1997-02-01), Hull et al.
patent: 5608324 (1997-03-01), Yoshida
patent: 5619117 (1997-04-01), Koenck
patent: 5654623 (1997-08-01), Shiga et al.
patent: 5662174 (1997-09-01), Vermilyer
patent: 5769657 (1998-06-01), Kondo et al.
patent: 5872444 (1999-02-01), Nagano et al.
patent: 5902105 (1999-05-01), Uejima
patent: 195 20 765 (1995-12-01), None
patent: 2 302 202 (1997-01-01), None
patent: 4-281332 (1992-10-01), None
patent: 4-351428 (1992-12-01), None
patent: 4-351427 (1992-12-01), None
Horikawa Kazuyoshi
Matsunaga Yutaka
Muramatsu Tomoo
Sakoh Masahiko
Sugiura Masatoshi
Foley Hoag & Eliot LLP
Makita Corporation
Tso Edward H.
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