Power tool
To provide a power tool which can supply electric power again from a battery even in a case where the supply of electric power from the battery is stopped by an over-discharge detection means. A power tool 1 includes an FET driving circuit 36 which permits the supply of electric power again to a motor 31 from a battery pack 2 in response to the turning-on of a trigger switch 33 even in the case where the battery pack 2 is placed in an over-discharge state and so the supply of electric power to the motor 31 from the battery pack 2 is stopped.
1. A power tool, comprising:
a tool main body having a motor configured to rotate in a first direction and a second direction;
a battery pack which supplies electric power to the motor;
detection means which detects a battery voltage of the battery pack;
protection means which stops supply of the electric power to the motor from the battery pack when the motor is rotating in the first direction and the battery voltage detected by the detection means is a predetermined value or less;
determining means which determines whether an instruction from a user is to rotate the motor in the first direction or the second direction after the stop of the supply of the electric power to the motor by the protection means; and
permission means which maintains the stop of the supply of the electric power to the motor when it is determined that the instruction from the user is to rotate the motor in the first direction and permits the supply of the electric power again to the motor when it is determined that the instruction from the user is to rotate the motor in the second direction.
2. The power tool according to claim 1 , further comprising:
a changeover switch which changes a rotation direction of the motor, wherein
the permission means permits the supply of the electric power again to the motor from the battery pack when the charge-over switch selects one of rotation directions.
3. The power tool according to claim 1 , wherein the permission means permits the supply of the electric power again to the motor from the battery pack when there is the instruction from a user within a predetermined time period after the protection means stops the supply of the electric power to the motor from the battery pack.
4. The power tool according to claim 1 , wherein the permission means permits the supply of the electric power again to the motor from the battery pack when there is the instruction from a user until the motor rotates by a predetermined number of revolution after the protection means stops the supply of the electric power to the motor from the battery pack.
5. The power tool according to claim 1 , wherein the protection means stops again the supply of the electric power to the motor from the battery pack upon lapse of a predetermined time after the permission means permits the supply of the electric power again to the motor from the battery pack in accordance with the instruction from a user.
6. The power tool according to claim 1 , wherein the protection means stops again the supply of the electric power to the motor from the battery pack when the motor rotates by a predetermined number of revolution after the permission means permits the supply of the electric power again to the motor from the battery pack in accordance with the instruction from a user.
7. The power tool according to claim 1 , wherein the battery pack includes a lithium battery.
8. The power tool according to claim 1 , wherein the protection means is provided on the battery pack side.
9. The power tool according to claim 1 , wherein the detection means is provided on the battery pack side.
10. The power tool according to claim 1 , further comprising a deceleration mechanism which decelerates a rotation speed of the motor and transmits the decelerated rotation to a tip end tool attached to the tool main body.
11. The power tool according to claim 1 , wherein the protection means includes:
switching means which is disposed between the motor and the battery pack and is capable of being turned on and off; and control means which turns the switching means off when the battery voltage detected by the detection means is the predetermined value or less.
12. The power tool according to claim 11 , wherein the permission means by-passes the switching means thereby to permit again the supply of the electric power to the motor from the battery pack.
13. The power tool according to claim 11 , wherein the switching means is an FET.
14. The power tool according to claim 1 , further comprising conversion mean which converts a rotation driving force of the motor into a shearing force.
15. The power tool according to claim 14 , wherein the conversion mean rotates a tip end tool attached to the tool main body.
16. The power tool according to claim 14 , wherein the conversion mean linearly moves reciprocally a tip end tool attached to the tool main body.
17. A battery pack for supplying electric power to a motor included in a tool main body of a power tool, the motor configured to rotate in a first direction and a second direction, the battery pack comprising:
detection means which detects a battery voltage of the battery pack; and
protection means which stops supply of the electric power to the motor from the battery pack when the motor is rotating in the first direction and the battery voltage detected by the detection means is a predetermined value or less;
and the power tool comprising:
determining means which determines whether an instruction from a user is to rotate the motor in the first direction or the second direction after the stop of the supply of the electric power to the motor by the protection means; and
permission means which maintains the stop of the supply of the electric power to the motor when it is determined that the instruction from the user is to rotate the motor in the first direction and permits the supply of the electric power again to the motor when it is determined that the instruction from the user is to rotate the motor in the second direction.
18. The battery pack according to claim 17 , wherein the release of the stop of the supply of the electric power to the motor from the battery pack is performed by the protection means, in accordance with the instruction from a user.
19. The battery pack according to claim 17 , wherein the protection means stops again the supply of the electric power to the motor from the battery pack upon lapse of a predetermined time after the supply of the electric power is permitted again to the motor from the battery pack in accordance with the instruction from a user.
20. The battery pack according to claim 17 , wherein the protection means stops again the supply of the electric power to the motor from the battery pack when the motor rotates by a predetermined number of revolutions after the supply of the electric power is permitted again to the motor from the battery pack in accordance with the instruction from a user.
21. The battery pack according to claim 17 , wherein the battery pack includes a lithium battery.
22. The battery pack according to claim 17 , wherein
the protection means includes:
switching means which is disposed between the motor and a battery included in the battery pack and is capable of being turned on and off; and
control means which turns the switching means off when the battery voltage detected by the detection means is the predetermined value or less.
23. The power tool according to claim 22 , wherein the switching means is an FET.
24. A method for controlling a power tool having a tool body, a motor, and a battery pack which supplies electric power to a motor, and detection means which detects a battery voltage of the battery pack, the method comprising:
rotating the motor in a first direction;
stopping the supply of electric power to the motor when the motor is rotating in the first direction and the battery voltage detected by the detecting means is a predetermined value or less;
determining whether an instruction from a user is to rotate the motor in the first direction or the second direction after the stop of the supply of electric power to the motor; and
maintaining the stop of the supply of the electric power to the motor when the instruction form the user is to rotate the motor in the first direction and permitting the supply of the electric power again to the motor when the instruction from the user is to rotate the motor in the second direction.