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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.

Inactive Publication Date: 2010-06-16
PANASONIC ELECTRIC WORKS POWER TOOLS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the rotor is a rotating body, it is almost impossible to detect the temperature of the rotor
Due to the large heat capacity of the motor housing, sometimes the motor housing may smoke before the rotor temperature rises

Method used

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Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0027] refer to Figure 1A , the rechargeable electric power tool of this embodiment is used as an electric driver. The power tool includes a rotary output section 1 for fixing a tip driving tool; a motor 4 that drives the rotary output section 1 through a gearbox 3 serving as a speed reducer; a battery pack 2 serving as a driving power source for the motor 4 (ie, a secondary battery); and a trigger switch 5 that is switched (on or off) by the user's operation of the trigger lever 5 a to turn on or off the rotation operation of the motor 4 .

[0028] The motor 4 is accommodated in the tool body 6 . The battery pack 2 is removably mounted to a battery pack mounting portion 6 c provided at the lower end of the grip portion 6 a of the tool body 6 . The trigger switch 5 is fixed in a switch block 8 made of resin provided in the tool body 6 . Six (plural) batteries 2a are arranged in the battery pack 2 in a series state. according to Figure 1A In the shown rechargeable electric...

no. 2 example

[0074] The configuration of the rechargeable power tool of the present embodiment is the same as that of Fig. 1 and figure 2 The power tool of the first embodiment shown in is the same. Common parts will be denoted by like reference numerals, and descriptions thereof will be omitted.

[0075] According to the rechargeable power tool of this embodiment, the first temperature threshold T is set for the first thermistor 9 arranged on the wire 7 th1 , than the first temperature threshold T th1 Lower preset temperature difference ΔT s1 The second temperature threshold T th2 , The growth rate of the first preset temperature (ΔT / Δt) s1 and than the second temperature threshold T th2 Lower preset temperature difference ΔT s2 The third temperature threshold T th3 . Furthermore, a first temperature threshold value T is set for the second thermistor 9a arranged in the motor housing 4a tha , than the first temperature threshold T tha Lower preset temperature difference ΔT sa T...

no. 3 example

[0104] The configuration of the rechargeable power tool of the present embodiment is the same as that of Fig. 1 and figure 2 The power tool of the first embodiment shown in is the same. Common parts will be denoted by like reference numerals, and descriptions will be omitted.

[0105] According to the rechargeable power tool of this embodiment, for the first thermistor 9 arranged on the wire 7, the first temperature threshold T is set th1 , than the first temperature threshold T th1 Lower preset temperature difference ΔT s1 The second temperature threshold T th2 , The growth rate of the first preset temperature (ΔT / Δt) s1 and than the second temperature threshold T th2 Lower preset temperature difference ΔT s2 The third temperature threshold T th3 . Furthermore, for the second thermistor 9a arranged in the motor housing 4a, a first temperature threshold T tha , than the first temperature threshold T tha Lower preset temperature difference ΔT sa The second temperatu...

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PUM

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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.

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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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B25F5/00
CPCB25F5/008B25F5/00H02J7/0063H02J7/007192
Owner PANASONIC ELECTRIC WORKS POWER TOOLS
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