JP2012035384A - Tool control device, tool control unit, and power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect switch-off by a simple structure in a power tool system in which a trigger switch and an FET for pulse control are installed between a secondary battery and a motor.SOLUTION: A power tool includes: a motor 1a; a trigger switch 1b which is serially connected to the motor 1a, and can be arbitrarily turned on/off; a battery group 41 for feeding power to the motor 1a; an FET 31 which is a current route formed between the motor 1a and the battery group 41 and which is arranged on the negative electrode side of the battery group 41; a micro computer 35 which controls the FET 31 so as to repeatedly operate on/off; a voltage buffer circuit 33 which inputs a voltage on the negative electrode side of the battery group 41 in the FET 31 and maintains the voltage; and a power supply circuit 32 which feeds the power of the battery group 41 to the micro computer 35 and feeds or shut off the power of the battery group 41 to the micro computer 35 on the basis of the voltage of the voltage buffer circuit 33.

Description

  The present invention relates to a power tool that drives a motor with a predetermined effective voltage lower than a battery voltage by using a secondary battery as a drive source and driving a switching element in pulses.

In a power tool that uses a secondary battery as a drive source, a switching element such as an FET is arranged in the current path between the motor and the secondary battery, and the switching element is pulse-controlled to achieve a desired voltage lower than the battery voltage of the secondary battery. An electric tool for driving a motor with an effective voltage of is disclosed. The driving of the switching element is controlled by a microcomputer, and the microcomputer operates by supplying power from a secondary battery (see Patent Document 1).

JP-A-2005-224909

  In Patent Document 1, the power supply to the microcomputer is switched in conjunction with the start and stop of use of the electric tool. However, since the stop of use of the tool is detected by the current flowing through the motor, the current flowing through the motor is When the number is small, it is considered that the tool is erroneously determined to have stopped despite the current detection error, and the power supply to the microcomputer is interrupted.

  This invention is made | formed in view of the said background, and is providing the electric tool etc. which can detect the operation state of a tool correctly.

  Another object of the present invention is to provide an electric tool or the like that can reliably detect that the tool has been stopped.

  Furthermore, the other object of this invention is to provide the electric tool etc. which can aim at the low reduction of a secondary battery appropriately.

  In order to solve the above-mentioned problems, in the invention of claim 1, a motor, a trigger switch connected in series to the motor and arbitrarily turn on / off, a battery pack for supplying power to the motor, and between the motor and the battery pack are provided. A switching element disposed on the negative electrode side of the battery pack, a control unit for controlling the switching element to repeatedly turn on and off, and a voltage on the negative electrode side of the battery pack among the switching elements. A voltage buffer circuit that holds the voltage and supplies the battery pack power to the control unit, and supplies the battery pack power to the control unit based on the voltage of the voltage buffer circuit. And a power supply circuit for cutting off.

  According to a second aspect of the present invention, the power supply circuit includes a switch circuit that inputs the voltage of the voltage buffer circuit and performs power supply to the internal circuit from the battery pack or power-off operation.

  The invention of claim 3 is characterized in that the voltage buffer circuit is provided with a smoothing circuit for smoothing a voltage generated in the switching element.

  The invention of claim 5 is characterized in that the voltage buffer circuit is provided with a backflow prevention diode for preventing discharge from the smoothing circuit to the switching element.

  The invention according to claim 5 is characterized in that the switching element is formed of a field effect transistor.

  In the invention of claim 6, an output adjustment unit capable of arbitrarily adjusting the output of the tool is provided, and the control unit adjusts the duty ratio of the pulse signal output to the switching element according to the output set by the output adjustment unit. It is characterized by.

  According to a seventh aspect of the present invention, the control unit includes an input terminal for inputting a stop signal from the battery pack, and stops driving of the switching element when the stop signal is input from the battery pack.

  The invention according to claim 8 is characterized in that it is provided with notifying means for notifying abnormality when the driving of the switching element is stopped.

  The invention according to claim 9 is a tool control device for controlling power supply from the battery pack to the electric tool connected to the electric tool, the positive electrode connecting terminal and the negative electrode connecting terminal connected to the pair of discharge terminals of the battery pack; A power supply terminal connected to the pair of discharge terminals of the battery pack, and a current path formed between the battery pack and the power tool, and one power source A switching element that is connected between the supply terminal and the negative connection terminal, repeatedly operates on and off, a voltage applied to the switching element, and a voltage buffer circuit that holds this voltage, and is connected to the positive connection terminal and the negative connection terminal And a power supply circuit for supplying power to the internal circuit based on the voltage of the voltage buffer circuit or for cutting off the power. It is.

  According to a tenth aspect of the present invention, the power supply circuit includes a switch circuit that inputs the voltage of the voltage buffer circuit and performs power supply to the internal circuit from the battery pack or power-off operation.

  The invention of claim 11 is characterized in that the voltage buffer circuit is provided with a smoothing circuit for smoothing a voltage generated in the switching element.

  The invention of claim 12 is characterized in that the voltage buffer circuit is provided with a backflow prevention diode for preventing discharge from the smoothing circuit to the switching element.

  The invention according to claim 13 is characterized in that the switching element is formed of a field effect transistor.

  The invention according to claim 14 controls the switching operation of the switching element, and includes a control unit that outputs a pulse signal to the switching element, and an output adjustment unit that can arbitrarily adjust the output of the tool, and adjusts the output. The control unit adjusts the duty ratio of the pulse signal output to the switching element according to the output set by the unit.

  According to a fifteenth aspect of the present invention, the control unit includes an input terminal for inputting a stop signal from the battery pack, and stops driving of the switching element when the stop signal is input from the battery pack.

  The invention according to claim 16 is characterized in that it is provided with notifying means for notifying abnormality when the driving of the switching element is stopped.

  The invention according to claim 17 includes the tool control device according to any one of claims 9 to 16 and a battery pack.

  The invention according to claim 18 is an electric tool system comprising the tool control device according to any one of claims 9 to 16 and an electric tool connected to the tool control device, wherein the electric tool is a pair of power supplies. A pair of power input terminals connected to the terminals, an electric motor connected between the pair of power input terminals, and directly connected to each other and a drive switch are provided.

  The invention of claim 19 is an electric tool system comprising the tool control device according to any one of claims 9 to 16, a battery pack, and an electric tool connected to the tool control device. A pair of power input terminals connected to the pair of power supply terminals, an electric motor connected between the pair of power input terminals, and directly connected to each other, and a drive switch are provided.

  According to the present invention, even in an electric tool that controls the voltage applied to the motor by repeatedly turning on and off the switching element, when the trigger switch of the tool is turned off, the voltage of the voltage buffer circuit is also lost, With this, it is possible to accurately detect that the trigger switch has been turned off.

  Further, during the tool operation, the voltage is maintained by the voltage buffer circuit, and the power supply circuit can be kept on.

  Furthermore, since the power supply to the control unit is interrupted when the trigger switch is turned off, the power consumption of the battery pack can be reduced.

The circuit diagram which shows one Embodiment of the electric tool system which concerns on the Example of this invention. The flowchart which shows the control content of the microcomputer of FIG.

  FIG. 1 is a circuit diagram showing an embodiment of the present invention. The electric power tool system of the present embodiment includes an electric power tool 1 and a control unit 2 that supplies power to the electric power tool 1 and controls its operation. The electric tool 1 is, for example, a sprayer, and pumps a liquid medicine stored in a medicine tank with a DC motor 1a and ejects it from a nozzle in a mist form.

  The direct current motor 1a of the sprayer 1 is provided with a trigger switch 1b connected in series to the direct current motor 1a, and the power supply to the motor 1a is switched by a user on / off operation. A pair of power supply terminals 1c and 1d for receiving power supply from the control unit 2 are connected to a series circuit of the motor 1a and the trigger switch 1b. The power terminal 1c is connected to the power supply terminal 20A on the positive side of the control unit 2, and the power terminal 1d is connected to the power supply terminal 20B on the negative side of the control unit.

  The control unit 2 includes a tool control device 3 that controls power supply to the DC motor 1a of the sprayer 1, and a battery pack 4 that supplies power to the tool control device 2 and supplies power to the DC motor 1a. .

[Configuration of tool control unit]
The tool control device 3 includes a pair of power supply terminals 20A and 20B connected to the power terminals 1C and 1D of the sprayer 1 as described above. The power supply terminal 20A functions as a positive terminal, and the power supply terminal 20B functions as a negative terminal. Further, a positive electrode connection terminal 30A and a negative electrode connection terminal 30B connected to the pair of positive and negative discharge terminals 40A and 40B of the battery pack 4 are provided. Then, the power supply terminal 20A and the positive electrode connection terminal 30A are connected, and the power supply terminal 20B and the negative electrode connection terminal 30B are connected to form a current path between the battery pack 4 and the DC motor 1a. Electric power from the battery pack 4 can be supplied to the DC motor 1a.

  Between the power supply terminal 20B and the negative electrode connection terminal 30B, an N-type field effect transistor 31 (hereinafter referred to as FET 31) which is a switching element is disposed. The FET 31 has a drain terminal connected to the power supply terminal 20B and a source terminal connected to the negative electrode connection terminal 30B. The FET 31 is configured such that a PWM control signal from a microcomputer 35, which will be described later, is input to the gate terminal, and repeatedly turns on and off while the sprayer 1 is in operation.

  A power supply circuit 32 for supplying power from the battery pack 4 to the internal circuit of the tool control device 3 is connected between the positive electrode connection terminal 30A and the negative electrode connection terminal. The power supply circuit 32 includes two FETs 321 and 322 and resistors 323 and 324. The P-type FET 321 is connected to the power supply line and functions as a switch for supplying power from the battery pack 4 and shutting off the power. The source terminal is connected to the positive connection terminal 30A, and the drain terminal is a constant voltage described later. A circuit 34 is connected. A resistor 323 for generating a source-gate voltage is connected between the source terminal and the gate terminal. The N-type FET 322 functions as a switch for turning on / off the FET 321 based on the voltage of the voltage buffer circuit 33 described later. The drain terminal is connected to the gate terminal of the FET 321 via the resistor 324, and the source terminal is grounded. Connected to the line. The voltage of the voltage buffer circuit 33 is input to the gate terminal.

  The voltage buffer circuit 33 is a circuit for inputting the drain voltage of the FET 31 and maintaining the voltage for a predetermined time. The voltage buffer circuit 33 includes resistors 331 and 332 that divide the drain voltage of the FET 31. The resistors 331 and 332 are connected in series, the resistor 331 is connected to the drain terminal of the FET 31, and the resistor 332 is connected to the ground line. A smoothing capacitor 333 is connected in parallel to the resistor 332, and the voltage of the capacitor 333 is input to the gate terminal of the FET 322. Between the resistor 331 and the drain terminal of the FET 31, a backflow prevention diode 334 for preventing the electric charge accumulated in the capacitor 333 from being discharged through the FET 31 is disposed. The diode 334 has an anode connected to the drain terminal of the FET 31 and a cathode connected to the resistor 331.

  A constant voltage circuit 34 that converts the voltage of the battery pack 4 into a predetermined voltage is connected to the power supply circuit 32. The constant voltage circuit 34 supplies a predetermined drive voltage to a microcomputer 35 and an overdischarge warning LED 36 described later.

  A voltage detection circuit 38 that detects the voltage of the battery pack 4 is connected to the input side of the constant voltage circuit 34, and an overdischarge signal is output to the microcomputer 35 when the voltage of the battery pack 4 falls below a predetermined voltage.

  The tool control device 3 is provided with an adjustment dial 37 for adjusting the output of the sprayer 1, and the user can arbitrarily set the dial to adjust the output. The dial value set by the adjustment dial 37 is input to the microcomputer 35.

  The microcomputer 35 operates based on a predetermined control program, and details will be described later.

  A flywheel diode 39 for stopping the motor 1a is connected between the power supply terminals 20A and 20B.

[Battery pack configuration]
The battery pack 4 is a general-purpose battery pack widely used in electric tools. Inside the battery pack 4 is housed a battery set 41 in which three lithium ion battery cells are connected in series. The positive electrode of the battery set 41 is connected to the positive electrode discharge terminal 40A, and the negative electrode is connected to the negative electrode discharge terminal 40B. It is connected to the. Also, a protection IC 42 for monitoring the voltage of each battery cell is housed inside the battery pack 4 and outputs an overdischarge signal when any one of the battery cells falls below a predetermined voltage. The overdischarge signal is output to the microcomputer 35 of the tool control device 3 through the LD terminal 40C. The protection IC 42 detects the current flowing through the battery set using the current detection resistor 43, and transmits a stop signal to the microcomputer 35 via the LD terminal when it is determined that the current exceeds a predetermined value.

  Hereinafter, the operation of this embodiment will be described. First, when the user turns on the trigger switch 1b in order to use the tool, the microcomputer 35 is not activated at the moment of turning on, and the FET 31 controlled by the microcomputer 35 is also in the off state. At this time, the drain voltage of the FET 31 is the potential of the battery voltage of the battery set 41 in the battery pack 4 via the switch 1b and the motor 1a. The potential of the battery voltage is divided by the resistor 331 and the resistor 332 via the diode 334 and input to the gate of the FET 322, and the FET 322 is turned on. When the FET 322 is turned on, a value obtained by dividing the battery voltage by the resistors 323 and 324 is input to the gate of the FET 321 and the FET 321 is turned on. When the FET 321 is turned on, a drive voltage is input to the microcomputer 35 via the constant voltage circuit 34, and the microcomputer 35 is activated. When the microcomputer 35 is activated, a PWM control signal is output from the output port of the microcomputer 35 to the gate terminal of the FET 31 in accordance with the dial setting value of the dial 37 set by the user, and an effective voltage corresponding to the duty ratio of this signal is generated by the motor. The motor is driven at a desired rotational speed.

  At this time, the voltage input to the gate of the FET 322 is applied to the voltage dividing resistors 331 and 332 through the switch 1b and the motor 1a while the FET 31 is off. At the same time, the capacitor 333 is charged within the range of the divided voltage value of the resistor 332.

  Further, during the period when the FET 31 is on, the gate voltage of the FET 31 is reduced to almost the ground potential. During this period, the charging voltage of the capacitor 333 is applied to the gate of the FET 322, so that the FETs 321 and 322 are kept on. Further, the charge accumulated in the capacitor 333 by the diode 334 is not discharged through the FET 31, and the capacitor voltage can be maintained.

  Thereafter, even if the FET 31 is repeatedly turned on and off, a predetermined voltage is applied to the gate of the FET 31, the FETs 332 and 331 are kept on, and the power supply to the microcomputer 35 is maintained.

  In the present embodiment, the duty ratio of the PWM control signal output from the microcomputer 35 to the FET 31 is set in the range of 10% to 50% according to the setting value of the dial 37. Therefore, when the duty ratio is set to 50%, the on-period of the FET 31 is the longest. Therefore, even when the time constant of the resistor 332 and the capacitor 333 is set to this duty ratio, the gate voltage of the FET 322 can be maintained. Just set it up.

  Further, when the trigger switch 1b is turned off, the drain voltage of the FET 31 is not input to the gate of the FET 322 via the diode 334, so the voltage of the capacitor 333 is discharged via the resistor 332, and the gate voltage of the FET 322 is lowered. The FET 322 is turned off. When the FET 322 is turned off, the FET 321 is also turned off, and the power supply from the battery pack 4 to the microcomputer 35 is cut off.

  Next, the operation of the present invention will be described using a flowchart executed by the microcomputer 35 of FIG. First, it is determined whether or not the microcomputer 35 has detected an overdischarge signal output from the protection IC 42 in the battery pack 4 during overdischarge (step 201). If it is detected, the overdischarge warning LED 37 is turned on to notify the user that the overdischarge state is present (step 202). In this case, the PWM signal is not output to the FET 31 and remains off (step 209). If it is determined in step 201 that there is no overdischarge state, the setting value of the dial 37 set by the user is detected (step 203). Next, a PWM control signal for controlling the FET 31 is output according to the setting value of the dial 37 detected in step 203 (step 204).

  That is, when the output is set to a high output, the effective voltage applied to the DC motor 1a is increased by setting the duty ratio of the PWM control signal high in order to increase the ON time of the FET 31. In addition, when the output is set to a low output, the effective voltage applied to the DC motor 1b is lowered by setting the duty ratio of the PWM control signal low in order to shorten the off time of the FET 31. In this way, the effective voltage applied to the motor 1a is controlled.

Next, it is determined whether or not the overdischarge warning LED 36 is on (step 205). If the overdischarge warning LED 36 is turned on in step 205, it is already overdischarged, so the routine proceeds to step 208. If the overdischarge warning LED 36 is not turned on at step 205, the battery is not in an overdischarge state at the present time. Next, at step 206, the battery voltage detection circuit 38 determines whether or not the battery voltage is equal to or lower than a predetermined value (step 206). If it is determined in step 206 that the battery voltage is equal to or lower than the predetermined value, the overdischarge warning LED 36 is turned on to warn the user that the battery is in an overdischarged state (step 207). If the battery voltage is not less than or equal to the predetermined value in step 206, it is determined whether or not the microcomputer 35 has detected an overdischarge signal output from the protection IC 42 in the battery pack 4 during overdischarge (step 208). If an overdischarge signal is detected in step 208, the output is stopped (step 209). In step S209, it is maintained while the trigger switch 1b is on. When the trigger switch 1b is turned off, the voltage of the voltage buffer circuit 3 disappears as the drain voltage of the FET 31 disappears, the power supply circuit 32 turns off, and the power supply to the microcomputer 35 is shut off. When the trigger switch 1b is turned on again, power is supplied to the microcomputer 35, and processing is executed according to the flow of FIG.
If no overdischarge signal is detected in step 209, the process returns to step 203.

  The operation at the time of driving the tool has been described above. However, when the trigger switch 1b is turned off while the tool is driven, the connection between the microcomputer 35 and the battery pack 4 is cut off as described above, so that the motor 1a is stopped. .

  According to the present embodiment, the tool system performs control to change the effective voltage applied to the motor by repeatedly turning the FET 31 on and off, and the voltage buffer circuit 33 maintains the voltage of the FET 31 to The supply circuit can be kept on. When the trigger switch 1b is turned off, the voltage of the voltage buffer circuit 33 is also lost, and the power supply circuit 32 shuts off the power supply to the microcomputer 35. Therefore, it is possible to accurately detect the trigger switch 1b being turned off. it can. Therefore, it is possible to accurately detect the operation state of the tool with a simple configuration. As a result, since the power supply to the microcomputer 35 is cut off when the trigger switch 1b is turned off, the power consumption of the battery pack 4 can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Sprayer (tool), 1a ... Motor, 1b ... Trigger switch, 1c, 1d ... Power supply terminal, 2 ... Tool control unit, 3 ... Tool control device, 4 ... Battery pack, 20A, 20B ... power supply terminal, 30A ... positive electrode connection terminal, 30B ... negative electrode connection terminal, 31 ... FET (switching element), 32 ... power supply circuit, 33 ..Voltage buffer circuit 34 ... constant voltage circuit 35 ... microcomputer 36 ... over discharge warning LED 37 ... dial 38 ... voltage detection circuit 40A, 40B ... Discharge terminal, 41 ... battery set, 321,322 ... FET, 331,332 ... resistor, 333 ... capacitor, 334 ... diode

Claims (19)

A motor,
A trigger switch connected in series to the motor and can be turned on and off arbitrarily,
A battery pack for supplying power to the motor;
A current path formed between the motor and the battery pack, the switching element disposed on the negative electrode side of the battery pack;
A controller that controls the switching element to repeatedly turn on and off;
A voltage buffer circuit for inputting a voltage applied to the switching element and holding the voltage;
A power tool comprising: a power supply circuit that supplies power to the control unit based on a voltage of the voltage buffer circuit, or that cuts off the power. The power supply circuit is
The power tool according to claim 1, further comprising a switch circuit that inputs a voltage of the voltage buffer circuit and performs power supply or power-off operation from the battery pack to the control unit.   The power tool according to claim 2, wherein the voltage buffer circuit includes a smoothing circuit that smoothes a voltage generated in the switching element.   The power tool according to claim 3, wherein the voltage buffer circuit includes a backflow prevention diode that prevents discharge from the smoothing circuit to the switching element.   The tool control device according to claim 1, wherein the switching element includes a field effect transistor. An output adjustment unit capable of arbitrarily adjusting the output of the tool;
The power tool according to any one of claims 1 to 5, wherein the control unit adjusts a duty ratio of a pulse signal output to the switching element in accordance with an output set by the output adjustment unit. .   The electric control according to claim 6, wherein the control unit includes an input terminal that inputs a stop signal from the battery pack, and stops the driving of the switching element when the stop signal is input from the battery pack. tool.   The power tool according to claim 7, further comprising notification means for notifying abnormality when driving of the switching element is stopped. A tool control device that is connected to a power tool and controls power supply from a battery pack to the power tool,
A positive connection terminal and a negative connection terminal connected to a pair of discharge terminals of the battery pack;
A power supply terminal connected to the power tool and connected to a pair of discharge terminals of the battery pack; and a current path formed between the battery pack and the power tool; A switching element that is connected between the power supply terminal and the negative electrode connection terminal and repeatedly operates on and off,
A voltage buffer circuit for inputting a voltage applied to the switching element and holding the voltage;
A power supply circuit that is connected to the positive electrode connection terminal and the negative electrode connection terminal and that supplies power to the internal circuit based on the voltage of the voltage buffer circuit, or that cuts off the power. Tool control device. The power supply circuit is
The tool control device according to claim 9, further comprising a switch circuit that inputs a voltage of the voltage buffer circuit and performs power supply or power-off operation from the battery pack to the internal circuit.   The tool control apparatus according to claim 10, wherein the voltage buffer circuit includes a smoothing circuit that smoothes a voltage generated in the switching element.   The tool control device according to claim 11, wherein the voltage buffer circuit includes a backflow prevention diode for preventing discharge from the smoothing circuit to the switching element.   The tool control device according to any one of claims 9 to 12, wherein the switching element includes a field effect transistor. A control unit that controls a switching operation of the switching element, and outputs a pulse signal to the switching element;
An output adjustment unit capable of arbitrarily adjusting the output of the tool,
The tool control according to any one of claims 9 to 13, wherein the control unit adjusts a duty ratio of a pulse signal output to the switching element in accordance with an output set by the output adjustment unit. apparatus.   The tool according to claim 14, wherein the control unit includes an input terminal for inputting a stop signal from the battery pack, and stops the driving of the switching element when the stop signal is input from the battery pack. Control device.   The tool control device according to claim 15, further comprising notification means for notifying abnormality when driving of the switching element is stopped.   A tool control unit comprising the tool control device according to any one of claims 9 to 16, and a battery pack. An electric tool comprising the tool control device according to any one of claims 9 to 16, and an electric tool connected to the tool control device,
The electric tool is
A pair of power input terminals connected to the pair of power supply terminals;
An electric tool comprising an electric motor and a drive switch connected between the pair of power input terminals and directly connected to each other. An electric tool comprising the tool control device according to any one of claims 9 to 16, a battery pack, and an electric tool connected to the tool control device,
The electric tool is
A pair of power input terminals connected to the pair of power supply terminals;
An electric tool comprising an electric motor and a drive switch connected between the pair of power input terminals and directly connected to each other.