JP2009072882A - Charging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool wherein the rotation of a motor is stopped when a switch trigger is pushed for a predetermined time to continuously rotate the motor. <P>SOLUTION: When the state where the trigger switch is pushed is continued for a predetermined time, a switching element constituting an inverter circuit is turned off to stop the operation of the motor. When the state where the trigger switch is not pushed is then recognized and the trigger switch is pushed again, the motor is operated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a brushless DC motor mounted on an electric tool.

  In general, an impact driver or the like equipped with a brushless DC motor is equipped with a control circuit for recognizing an operator's operation of a trigger switch and controlling the operation of the motor in accordance with the operation amount. For example, when the worker performs a light work that does not require a large force, such as tightening a small screw, the trigger switch is lightly pressed. The control circuit recognizes that the amount of operation of the trigger is small, and controls the motor according to the amount of operation, so that the operation can be performed with an appropriate load. Conversely, when a heavy work requiring a large force is performed, such as when a relatively long screw is tightened on a hard material, the trigger switch is strongly pressed. Also in this case, the control circuit recognizes that the operation amount of the trigger is large, and controls the motor in accordance with the operation amount, thereby enabling proper work.

Japanese Patent Application Laid-Open No. 5-220677

  In such an electric tool, since the motor is controlled in response to a delicate operation of the trigger switch, it is designed so that the trigger switch reacts sensitively. In other words, if the trigger switch is pushed even a little, the motor will rotate. For example, power tools are generally stored in a dedicated case and stored, but for some reason the case is not completely stored, and the switch is pushed when something touches the trigger switch, causing the motor to The case where it keeps turning is considered. For example, when the motor drive source is a lithium ion battery, the battery falls into an overdischarged state if the motor continues to rotate. When the lithium ion battery continues to be in an overdischarged state, copper is deposited and the electrodes are short-circuited. In the worst case, smoke and fire may occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric tool that stops rotation of a motor when a switch trigger is pressed for a predetermined time and the motor continues to rotate. Is to provide.

  In order to achieve the above object, the invention of claim 1 switches a brushless DC motor including a rotor having a permanent magnet and a stator having an armature winding, and a DC voltage supplied from an external power source. An inverter circuit that drives the brushless DC motor by switching energization to the stator windings of each phase, a trigger switch that operates the brushless DC motor by an operator's trigger operation, and an operation of the trigger switch is recognized. An electric tool comprising a control signal output unit for controlling a switching element constituting the inverter circuit according to the operation amount to control an applied voltage of the brushless DC motor, wherein the trigger switch is pressed If the operation state continues for a predetermined time or longer, the switching elements constituting the inverter circuit are turned off to stop the motor operation. Characterized in that the so that.

  According to a second aspect of the present invention, in order to achieve the above-described object, the trigger switch is pressed after the state in which the trigger switch is pressed continues for a predetermined time or longer to stop the motor. When the trigger switch is pressed again after recognizing a state that has not been detected, the motor is operated.

  An object of the present invention is to provide an electric tool that stops rotation of a motor when a switch trigger is pressed for a predetermined time and the motor continues to rotate.

  First, a battery-driven impact driver shown in FIG. 1 will be described as an example of an electric tool in an embodiment of the present invention.

  In FIG. 1, a power tool housing 101 includes a brushless DC motor 2, a control unit 6 for driving and controlling the brushless DC motor 2, and a transmission mechanism unit 104 for transmitting rotational power of the motor 102. Is housed. The rechargeable battery 1 is used as a voltage source for driving the motor. The voltage source for driving the motor is not limited to the rechargeable battery. The transmission mechanism 104 includes a speed reduction mechanism configured by a planetary gear 106 and a ring gear 107, and an impact mechanism configured by a spindle 108 and a hammer 109 urged by a spring 111 disposed on the spindle 108 so as to be movable back and forth. And an anvil 110 capable of holding the tip tool and a protrusion 112 for rotating the anvil 110 by applying a striking impact of the hammer 9 provided on the anvil 110. The operation of the transmission mechanism unit 104 during actual work will be described. While the load is small, rotation is transmitted as it is from the spindle 108 to the anvil 110 via the hammer 109. When the load increases, the hammer 109 alternately performs the reverse movement against the elastic force of the spring 111 and the forward movement while rotating in a state where the elastic force of the spring 111 is applied. During advance, the hammer 109 applies the impact force as a rotational force to the anvil 110 to perform a screw tightening operation. A switch trigger 9 for operating the brushless DC motor 2 is disposed in the center of the housing. The operator operates the power tool by operating the switch trigger 9.

  FIG. 2 shows the configuration of the control circuit 3 of the brushless DC motor 2 in this embodiment.

  A rechargeable battery 1 is a driving source of the DC brushless motor 2. Reference numeral 2 denotes a brushless DC motor, which includes a rotor 2b in which a plurality of permanent magnets 2a are embedded, and a stator 2c in which a stator winding 2d is wound around a plurality of salient poles. Yes. The structure of the rotor and the stator, such as the arrangement of the permanent magnets, the number of permanent magnets, and the number of salient poles of the stator, is not limited to that described above. Hall ICs 3, 4, and 5 are provided so as to correspond to the permanent magnet 2a of the rotor 2b, and the rotational position of the rotor 2b is detected. The motor control unit 6 in this configuration inputs the rotor rotation position detection signal detected by the Hall ICs 3, 4, and 5 to the output port 6b, and supplies the appropriate stator windings based on the information. And rotate the rotor. Further, based on the rotational position detection signal, the control unit 6 also detects the rotational speed of the motor.

  Reference numeral 6 denotes a control unit, which uses a microcomputer in this embodiment. The microcomputer as a control unit has an A / D port 6a, an input port 6b, and a timer 6c.

Reference numeral 7 denotes a three-phase inverter bridge that controls a current to be supplied to the brushless DC motor 2, and includes switching elements 7a, 7b, 7c, 7d, 7e, and 7f.
When the operator presses the switch trigger 8, the operator recognizes that the switch trigger has been pressed at the A / D port 6a of the control unit 6. Thereafter, the control unit 6 switches the switching elements 7a, 7b, 7c, 7d of the three-phase inverter bridge 7 via the gate driver 9 according to the operation amount of the switch trigger 8, that is, the input of the A / D port 6a of the control unit 6. , 7e, 7f are duty controlled by the timer module 6d.

  Next, an example of the operation in the present embodiment will be described using the flowchart of FIG. First, the control unit 6 detects whether or not the switch trigger has been pressed (step 301). Whether or not the switch trigger is pressed is determined depending on whether or not the input is recognized at the A / D port 6a of the control unit 6. When it is recognized in step 301 that the switch trigger has been pressed, the control unit 6 determines the gate driver according to the operation amount of the switch trigger recognized in step 301, that is, the input to the A / D port 6 a of the control unit 6. 10, the duty of the switching elements 7a, 7b, 7c, 7d, 7e, 7f of the three-phase inverter bridge 7 is controlled by the timer module 6c to rotate the motor (step 302).

Next, the control unit 6 detects whether or not the switch trigger has been pressed (step 303). Whether or not the switch trigger is pressed is determined depending on whether or not the input is recognized at the A / D port 6a of the control unit 6. If it is determined in step 303 that the trigger switch has not been pressed, that is, the trigger switch has not been pressed, the control unit 6 via the gate driver 10 switches the switching elements 7a, 7b, 7c, The motor is stopped by turning off 7d, 7e, and 7f (step 304). After the motor stops, the process returns to step 301 to detect again whether the trigger switch has been pressed. If it is determined in step 303 that the state where the trigger is pressed is continued, it is determined whether or not a predetermined time has elapsed since it was recognized that the trigger was turned on (step 305). If it is determined in step 305 that the predetermined time has not elapsed, the process returns to step 302 and the motor is continuously rotated based on the operation amount of the switch trigger. If it is determined in step 305 that the predetermined time has elapsed, the control unit 6 turns off the switching elements 7a, 7b, 7c, 7d, 7e, and 7f of the three-phase inverter bridge 7 via the gate driver 10. The motor is stopped (step 306). The predetermined time may be set to about 5 minutes, for example, but is not limited thereto.
Next, the control unit 6 detects whether or not the switch trigger is pressed (step 307). Whether or not the switch trigger is pressed is determined depending on whether or not the input is recognized at the A / D port 6a of the control unit 6. If it is determined in step 307 that the switch trigger is being pressed, that is, if the motor continues to rotate for a predetermined time after the trigger switch is pressed, the motor does not rotate if the switch trigger is kept pressed after the motor stops in step 306. Like that. If it is determined in step 307 that the switch trigger has not been pressed, the process returns to step 301 to wait for the switch trigger input.

The figure explaining an example of DC brushless motor. The figure explaining the outline of the motor drive control part in a present Example. The flowchart which showed an example of the operation | movement in a present Example.

Explanation of symbols

Reference numeral 1 is a rechargeable battery, 2 is a motor, 6 is a control unit, 7 is a three-phase inverter bridge, and 8 is a switch trigger.

Claims (2)

A brushless DC motor consisting of a rotor with a permanent magnet and a stator with an armature winding, and a DC voltage supplied from an external power source are switched to switch energization to the stator windings of each phase. An inverter circuit that drives the brushless DC motor, a trigger switch that operates the brushless DC motor by a trigger operation by an operator, and a switching that recognizes the operation of the trigger switch and configures the inverter circuit according to the operation amount And a control signal output unit for controlling an applied voltage of the brushless DC motor by controlling an element, and when the state where the trigger switch is pressed continues for a predetermined time or longer, the inverter circuit is An electric tool that stops the operation of the motor by turning off the constituent switching elements.   The electric power tool according to claim 1, wherein after the motor is stopped for a predetermined time or longer after the trigger switch is pressed as in claim 1, the state in which the trigger switch is not pressed is recognized. After that, when the trigger switch is pressed again, the electric tool operates the motor.

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