Rechargeable electric power tool

By setting a temperature detection unit on the motor wire and calculating the temperature growth rate, it determines the motor overload status and sets a restricted working mode, which solves the problem of difficulty in detecting high temperature of the motor coil with traditional technology, effectively prevents motor overload, and improves improve the safety and performance of power tools.
CN101733739AInactive Publication Date: 2010-06-16PANASONIC ELECTRIC WORKS POWER TOOLS
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
PANASONIC ELECTRIC WORKS POWER TOOLS
Publication Date
2010-06-16
Estimated Expiration
Not applicable · inactive patent
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Abstract

In a rechargeable electric power tool, upon changeover of a trigger switch, a microcomputer determines the magnitude relation between the detected temperature outputted from the first thermistor and the first temperature threshold value, the second temperature threshold value and the third temperature threshold value, and the magnitude relation between the first calculated temperature increase rate and the first preset temperature increase rate. If the detected temperature is determined to be greater than the first temperature threshold value or if the first calculated temperature increase rate is determined to be greater than the first preset temperature increase rate after the detected temperature has been determined to be greater than the second temperature threshold value, the microcomputer is set in a limited operation mode in which the revolution number of the motor is limited to a predetermined value or less.
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Description

technical field

[0001] The invention relates to a rechargeable power tool. Background technique

[0002] Conventionally, a known rechargeable power tool is used as an electric driving device or the like, which includes a motor driven by electric power supplied from a rechargeable battery pack, a field effect transistor (FET) used as a switching element for adjusting power distribution of the motor FET), and a microcomputer for controlling the rotation of the motor through the FET.

[0003] In such a rechargeable power tool, the motor is rotationally driven at maximum output power by turning on the FET and stopped by turning off the FET. The number of revolutions of the motor is controlled by driving the FET with pulse width modulation (PWM).

[0004] As one example of a rechargeable power tool, a power tool is proposed in which a temperature sensor is arranged in a battery of a battery pack. The temperature of the battery is detected by a temperature detection circuit con...

Claims

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