Electric power tool

Abstract

An electric power tool includes a motor; a battery unit for supplying an electric power for driving the motor; a driving force transmission mechanism for transmitting a driving force of the motor; a manipulation unit for receiving input data including a rotation number and an on/off manipulation of the motor; a motor control unit for controlling the motor based on the input data from the manipulation unit; and a temperature sensor for detecting a temperature of the battery unit as a temperature value. If the temperature value detected by the temperature sensor while being operated in an normal operation mode is higher than or equal to a first abnormal temperature value, the motor control unit determines that the battery unit is in an abnormal state, and converts an operation mode of the motor to a limited operation mode in which a rotation of the motor is stopped or suppressed.

1 . An electric power tool comprising:
 a motor;   a battery unit for supplying an electric power for driving the motor;   a driving force transmission mechanism for transmitting a driving force of the motor;   a manipulation unit for receiving input data including a rotation number and an on/off manipulation of the motor;   a motor control unit for controlling the motor based on the input data from the manipulation unit; and   a temperature sensor for detecting a temperature of the battery unit as a temperature value,   wherein, if the temperature value detected by the temperature sensor while being operated in an normal operation mode is higher than or equal to a first abnormal temperature value, the motor control unit determines that the battery unit is in an abnormal state, and converts an operation mode of the motor to a limited operation mode in which a rotation of the motor is stopped or suppressed.   
     
     
         2 . The electric power tool of  claim 1 , wherein, the motor control unit determines that the battery unit is in an abnormal state also in case the temperature value detected by the temperature sensor while being operated in the normal operation mode is lower than the first abnormal temperature value but higher than or equal to a second abnormal temperature value, and an increase rate of the temperature value is higher than or equal to a specific rate. 
     
     
         3 . The electric power tool of  claim 1 , wherein the motor control unit carries out a determination of the abnormal state only while the manipulation unit is being manipulated. 
     
     
         4 . The electric power tool of  claim 2 , wherein the motor control unit carries out a determination of the abnormal state only while the manipulation unit is being manipulated. 
     
     
         5 . The electric power tool of  claim 1 , wherein the motor control unit sets a maximum rotation number of the motor while being operated in the limited operation mode to be smaller than that of the motor while being operated in the normal operation mode. 
     
     
         6 . The electric power tool of  claim 2 , wherein the motor control unit sets a maximum rotation number of the motor while being operated in the limited operation mode to be smaller than that of the motor while being operated in the normal operation mode. 
     
     
         7 . The electric power tool of  claim 1 , wherein, if the temperature value detected by the temperature detector while being operated in the limited operation mode is equal to or smaller than a restoration temperature value, the motor control unit determines to return the operation to the normal operation mode, and converts the operation mode of the motor to the normal operation mode. 
     
     
         8 . The electric power tool of  claim 2 , wherein, if the temperature value detected by the temperature detector while being operated in the limited operation mode is equal to or smaller than a restoration temperature value, the motor control unit determines to return the operation to the normal operation mode, and converts the operation mode of the motor to the normal operation mode. 
     
     
         9 . The electric power tool of  claim 7 , wherein the motor control unit carries out a determination to return the operation to the normal operation mode only while the manipulation unit is not being manipulated. 
     
     
         10 . The electric power tool of  claim 8 , wherein the motor control unit carries out a determination to return the operation to the normal operation mode only while the manipulation unit is not being manipulated. 
     
     
         11 . The electric power tool of  claim 7 , wherein, when the manipulation unit is manipulated first after a determination to return the operation to the normal operation mode, the motor control unit executes a restoring operation mode, and converts the operation mode of the motor to the normal operation mode after completing the restoring operation mode, and
 wherein, in the restoring operation mode, a time period required for the rotation number of the motor to reach a number corresponding to the input data of the manipulation unit is set to be longer than that set in the normal operation mode.   
     
     
         12 . The electric power tool of  claim 8 , wherein, when the manipulation unit is manipulated first after a determination to return the operation to the normal operation mode, the motor control unit executes a restoring operation mode, and converts the operation mode of the motor to the normal operation mode after completing the restoring operation mode, and
 wherein, in the restoring operation mode, a time period required for the rotation number of the motor to reach a number corresponding to the input data of the manipulation unit is set to be longer than that set in the normal operation mode.   
     
     
         13 . The electric power tool of  claim 9 , wherein, when the manipulation unit is manipulated first after a determination to return the operation to the normal operation mode, the motor control unit executes a restoring operation mode, and converts the operation mode of the motor to the normal operation mode after completing the restoring operation mode, and
 wherein, in the restoring operation mode, a time period required for the rotation number of the motor to reach a number corresponding to the input data of the manipulation unit is set to be longer than that set in the normal operation mode.   
     
     
         14 . The electric power tool of  claim 10 , wherein, when the manipulation unit is manipulated first after a determination to return the operation to the normal operation mode, the motor control unit executes a restoring operation mode, and converts the operation mode of the motor to the normal operation mode after completing the restoring operation mode, and
 wherein, in the restoring operation mode, a time period required for the rotation number of the motor to reach a number corresponding to the input data of the manipulation unit is set to be longer than that set in the normal operation mode.   
     
     
         15 . The electric power tool of  claim 1 , further comprising:
 a load detector for detecting a load of the motor,   wherein the motor control unit stops the motor if a load value detected by the load detector while being operated in the limited operation mode exceeds a specific reference value for a specific period of time.   
     
     
         16 . The electric power tool of  claim 2 , further comprising:
 a load detector for detecting a load of the motor,   wherein the motor control unit stops the motor if a load value detected by the load detector while being operated in the limited operation mode exceeds a specific reference value for a specific period of time.   
     
     
         17 . The electric power tool of  claim 1 , further comprising:
 a power supply sustaining unit that serves to sustain or cut off a power supply to the motor control unit,   wherein, if the manipulation unit is not manipulated for a specific time period, the power supply sustaining unit cuts off the power supply to the motor control unit, the specific time period being set to be longer while being operated in the limited operation mode than that set while being operated in the normal operation mode.   
     
     
         18 . The electric power tool of  claim 2 , further comprising:
 a power supply sustaining unit that serves to sustain or cut off a power supply to the motor control unit,   
       wherein, if the manipulation unit is not manipulated for a specific time period, the power supply sustaining unit cuts off the power supply to the motor control unit, the specific time period being set to be longer while being operated in the limited operation mode than that set while being operated in the normal operation mode. 
     
     
         19 . The electric power tool of  claim 1 , wherein, a transmission failure temperature value is set such that, when a transmission failure occurs in a data transmission line connected between the temperature sensor and the motor control unit, the temperature value detected by the temperature sensor is smaller than the transmission failure temperature value, and
 wherein, if the temperature value detected by the temperature detector while being operated in the normal operation mode is equal to or smaller than the transmission failure temperature value, the motor control unit determines that the battery unit is in the abnormal state, and converts the operation mode of the motor to the limited operation mode regardless of the input data provided from the manipulation unit.   
     
     
         20 . The electric power tool of  claim 2 , wherein, a transmission failure temperature value is set such that, when a transmission failure occurs in a data transmission line connected between the temperature sensor and the motor control unit, the temperature value detected by the temperature sensor is smaller than the transmission failure temperature value, and
 wherein, if the temperature value detected by the temperature detector while being operated in the normal operation mode is equal to or smaller than the transmission failure temperature value, the motor control unit determines that the battery unit is in the abnormal state, and converts the operation mode of the motor to the limited operation mode regardless of the input data provided from the manipulation unit.