Power tool
First Claim
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1. A power tool configured to receive a secondary battery, the power tool comprising:
- a drive unit to which the secondary battery is connectable;
a voltage detecting unit configured to detect a battery voltage developed across the secondary battery;
a current detecting unit configured to detect a current flowing through the drive unit;
a storage device; and
a control unit configured to output a chopping control signal with a duty cycle changeable in accordance with the battery voltage detected by the voltage detecting unit, a voltage applied to the drive unit from the secondary battery being changed in accordance with the duty cycle changed by the control unit,wherein the secondary battery is one of a plurality of batteries including a first battery and a second battery, wherein the second battery has a greater voltage than thefirst battery; and
wherein the control unit is further configured to perform the following;
read a first allowable power dissipation value from the storage device;
set a first predetermined current value based on the first allowable power dissipation value and a detected battery voltage value of the first battery detected by the voltage detecting unit;
compare a current flowing in the drive unit detected by the current detecting unit to the first predetermined current value;
decrease the duty cycle of the chopping control signal when the detected current flowing in the drive unit has exceeded the first predetermined current value;
set a second predetermined current value, smaller than the first predetermined current value, based on the first allowable power dissipation value and a detected battery voltage value of the second battery detected by the voltage detecting unit;
compare the current flowing in the drive unit detected by the current detecting unit to the second predetermined current value; and
decrease the duty cycle of the chopping control signal when the detected current flowing in the drive unit has exceeded the second predetermined current value.
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Abstract
A power tool includes: a secondary battery; a drive unit; a detecting unit; and a control unit. The secondary battery has positive and negative terminals across which a battery voltage is developed. The drive unit is connected to the secondary battery. The detecting unit is configured to detect a current value and a voltage value supplied from the secondary battery to the drive unit. The control unit is configured to control an effective voltage and an effective current applied to the drive unit depending on a load imposed thereon to fall within an allowable power dissipation value.
38 Citations
7 Claims
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1. A power tool configured to receive a secondary battery, the power tool comprising:
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a drive unit to which the secondary battery is connectable; a voltage detecting unit configured to detect a battery voltage developed across the secondary battery; a current detecting unit configured to detect a current flowing through the drive unit; a storage device; and a control unit configured to output a chopping control signal with a duty cycle changeable in accordance with the battery voltage detected by the voltage detecting unit, a voltage applied to the drive unit from the secondary battery being changed in accordance with the duty cycle changed by the control unit, wherein the secondary battery is one of a plurality of batteries including a first battery and a second battery, wherein the second battery has a greater voltage than the first battery; and wherein the control unit is further configured to perform the following; read a first allowable power dissipation value from the storage device; set a first predetermined current value based on the first allowable power dissipation value and a detected battery voltage value of the first battery detected by the voltage detecting unit; compare a current flowing in the drive unit detected by the current detecting unit to the first predetermined current value; decrease the duty cycle of the chopping control signal when the detected current flowing in the drive unit has exceeded the first predetermined current value; set a second predetermined current value, smaller than the first predetermined current value, based on the first allowable power dissipation value and a detected battery voltage value of the second battery detected by the voltage detecting unit; compare the current flowing in the drive unit detected by the current detecting unit to the second predetermined current value; and decrease the duty cycle of the chopping control signal when the detected current flowing in the drive unit has exceeded the second predetermined current value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification