JP2008023645A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology by which a user can be positively notified of the switch-on in a power tool when a power is supplied to a switch for driving a motor locked in an on-state. <P>SOLUTION: This power tool is provided with a tip tool 117, a motor 111 rotating at a prescribed rotating speed and driving the tip tool 117, a power feed means 127 feeding a current to the motor 111, and an operation switch 123 capable of changing over an on-state for actuating the motor and an off-state for stopping the motor 111, and when a power feed mans 127 feeds power with the operation switch 123 locked in the on-state, actuates the motor 111 at a rotating speed lower than a prescribed rotating speed and notifying the user of turn-on of the operation switch 123 by the low-speed driving state of the tip tool 117 driven by the motor 111. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric tool that performs a predetermined machining operation on a workpiece by driving a tip tool with a motor, and in particular, a switch that is turned on and off by a user to drive or stop the motor is driven by the motor. The present invention relates to a technology for preventing a motor from restarting when electric power is supplied in a locked state in which it can be turned on.

In order to facilitate the continuous work, an electric tool provided with a mechanism (lock-on mechanism) that locks a motor driving switch in an on state is provided. In such a power tool with a lock-on mechanism, when the power is stopped due to a power failure, for example, when the power is stopped in a lock-on state with the switch turned on, Is provided with a restart prevention device that prevents the computer from restarting. Such a power tool restart prevention technique is disclosed in, for example, Japanese Patent No. 3092474 (Patent Document 1). In the above-mentioned patent publication, when power supply is stopped due to a power failure or the like during operation of the electric device, the restart of the motor is electrically prevented even if the operation switch is locked to the on state when the power supply is resumed after recovery from the power failure An electrical device is described having a start-up blocking device configured as described above.
However, the conventional power tool restart prevention technology described above prevents the motor from restarting when the power is turned on with the motor drive switch locked in the ON state. It is not intended to actively remind the user that the lock is on.
Japanese Patent No. 3092474

  The present invention has been made in view of such points, and in an electric tool, when the power is turned on with the motor driving switch locked in the on state, the switch is in the locked state. The purpose is to provide technology that actively informs users.

In order to achieve the above object, the invention described in each claim is configured.
According to the first aspect of the present invention, a tip tool that performs a predetermined machining operation on the workpiece, a motor that rotates at a predetermined rotational speed to drive the tip tool, and a power supply unit that supplies current to the motor. An electric tool having an operation switch that can be switched between an ON state for driving the motor and an OFF state for stopping the motor is configured. The “operation switch” in the present invention typically corresponds to a trigger switch that is biased to an off state by a spring and is turned on by being pulled by a user's finger. . In addition, the “power supply means” in the present invention includes both a method of supplying current to a motor from a power source such as a factory using an electric cord and a method of supplying current to a motor from a battery mounted on a tool body. In addition, the “electric tool” in the present invention is an electric work tool using a motor as a drive source, such as a work tool used for drilling work or tightening work, a work tool used for cutting work, cutting work, grinding work or polishing work, etc. Is widely included.
In the present invention, as a characteristic configuration, when the power supply means supplies power with the operation switch locked to the on state, the motor is driven at a rotational speed lower than a predetermined rotational speed, and is driven by the motor. The operation switch is in an on state according to the low-speed driving state of the tip tool to be operated. The “locked state” in the present invention is typically an aspect in which when a trigger switch as an operation switch is pulled, the trigger switch is locked (held) by a mechanical lock-on mechanism. This is the case. In the present invention, “when power supply is performed” refers to the case where power supply is resumed. For example, in the case of a method of driving a power tool using a power source of a factory or the like, recovery of the power failure after a power failure is achieved. If the power supply is resumed by the power supply, the power supply is resumed by inserting the plug of the electric cord of the power tool into an outlet provided on the wall or the like, or the rechargeable power tool using a battery as the power source, This is the case in which power supply is resumed by re-attaching the battery once removed from the battery holder part of the tool and recharged to the battery holder part. Further, in the present invention, “driving the motor at a rotational speed lower than a predetermined rotational speed” means that a current value smaller (lower) than a current value flowing during a machining operation is applied to a driving current value flowing to the motor driving circuit. The embodiment corresponds to this. The “low-speed driving state of the tip tool” in the present invention typically corresponds to a state in which the tip tool is driven at a moderate speed at which a predetermined machining operation cannot be performed.
According to the present invention, when the power supply means supplies power while the operation switch is locked to the ON state, the motor is driven at a rotational speed lower than a predetermined rotational speed, and the tip driven by the motor It is configured to notify that the operation switch is in the on state according to the low-speed driving state of the tool. Therefore, according to the present invention, it is possible not only to prevent the motor from being unexpectedly driven at a predetermined rotational speed, but also to drive the tip tool at a low speed different from the normal time, thereby turning the operation switch on. It is possible to actively inform the user that the device is locked.

(Invention of Claim 2)
According to the second aspect of the present invention, in the electric tool according to the first aspect, when the power supply means further includes a sound generator and the operation switch is locked in the on state. The sound generator is activated to notify that the operation switch is in the on state by the sound generated by the sound generator in addition to the low-speed driving state of the tip tool. The “sound generated by the sound generator” in the present invention is preferably a warning sound such as an emergency bell, a horn or a siren, but may be a sound other than the warning sound. According to the present invention, not only the low-speed operation of the tip tool but also the user can be surely noticed that the operation switch is locked in the ON state.

(Invention of Claim 3)
According to the invention described in claim 3, in the electric tool described in claim 1 or 2, the low speed driving state of the tip tool is performed as an intermittent operation. According to the present invention, when the power supply means resumes supplying power to the motor with the operation switch locked in the ON state, the tip tool is driven in an intermittent low-speed driving state, so that the tip tool can be operated. Can give change. For this reason, it is easy for the user to notice that the operation switch is locked in the ON state.

(Invention of Claim 4)
According to the fourth aspect of the present invention, the operation switch in the electric tool according to any one of the first to third aspects is in any one of an on state for driving the motor and an off state for stopping the motor. This is configured to output as an electric signal. The electric tool further includes a changeover switch and a control device. The changeover switch is provided in the motor drive circuit, and the drive circuit is in a first state in which a high current is energized, in a second state in which a low current is energized, or in a non-energized state. The switching operation is performed so as to set any one of the three states. The control device switches and controls the changeover switch to any one of the first state, the second state, and the third state based on the electrical signal output from the operation switch.
Further, the control device is driven by operating the changeover switch to the second state when the power supply means supplies power while an electric signal indicating that the operation switch is in the ON state is input. The circuit is switched to a current-carrying state at a low current, thereby driving the motor at a rotational speed lower than a predetermined rotational speed. Further, the control device is driven by operating the changeover switch to the third state when the power supply means supplies power while an electric signal indicating that the operation switch is in the OFF state is input. When the circuit is switched to a non-energized state and then an electric signal indicating that the operation switch has been switched to the on state is input, the switch is operated to the first state based on the input signal to drive the circuit. Is switched to an energized state at a high current, thereby driving the motor at a predetermined rotational speed. Note that, as the “changeover switch” in the present invention, typically, a semiconductor switch is preferably used.
According to the present invention, at the time of power feeding by the power feeding means, the motor is electrically controlled according to whether or not the operation switch is in the on state, so that the motor can be prevented from restarting with a simple structure. Is built.

  According to the present invention, in the electric tool, when the power is turned on while the motor driving switch is locked in the ON state, the technique is actively notified to the user that the switch is in the locked state. Will be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. This embodiment will be described by using a hand-held electric disc grinder used for polishing or grinding various workpieces such as metal, concrete and stone as an example of an electric tool. FIG. 1 is a perspective view showing the overall configuration of the electric disk grinder. An electric disc grinder 101 (hereinafter referred to as a grinder) according to the present embodiment has a major axis direction as a front-rear direction (the left-right direction in the drawing), and a main body as a tool main body including a motor housing 105 and a gear housing 107. The outline is constituted by the portion 103. The motor housing 105 is formed in a substantially cylindrical shape, and a drive motor 111 (see the circuit diagram in FIG. 2) is accommodated in the motor housing 105. The drive motor 111 corresponds to the “motor” in the present invention. In the present embodiment, a case where a current is supplied to the drive motor 111 from a power supply 127 (see the circuit diagram of FIG. 2) such as a factory using a power cord 119 is shown. The power source 127 corresponds to the “power supply unit” in the present invention.

  A power transmission mechanism (not shown for convenience) that transmits the rotation output of the drive motor 111 to the grindstone 117 is accommodated in the gear housing 107 connected to the front end portion of the motor housing 105. The grindstone 117 corresponds to the “tip tool” in the present invention. The rotational output of the drive motor 111 is transmitted as a rotational motion in the circumferential direction to the grindstone 117 through a power transmission mechanism. The grindstone 117 is disposed on one end side (front side) of the main body portion 103 in the long axis direction so that the rotation axis thereof is orthogonal to the long axis direction of the main body portion 103.

A main handle 109 is connected to the other end side (rear side) of the motor housing 105. The main handle 109 is provided such that the major axis direction thereof is the major axis direction of the main body 103. That is, the main handle 109 extends substantially linearly in the major axis direction of the main body 103. The main handle 109 is provided with a trigger 115 for switching a trigger switch 123 described later. The trigger 115 is attached to the main handle 109 so as to be rotatable about a rotation center (not shown for convenience) as a fulcrum, and by a spring (not shown) from the operation position side to the initial position (non-operation position) side. It is energized and is always in the initial position. The main handle 109 is provided with a mechanical lock-on mechanism 116 that can lock the trigger 115 in the operated position by pulling it for the convenience of continuous work.
A removable auxiliary handle 113 is provided on the side surface of the gear housing 107, and the auxiliary handle 113 is mounted so that the major axis direction thereof is substantially orthogonal to the major axis direction of the main body 103. An operator can hold the main handle 109 and the auxiliary handle 113 with his / her hand and rotationally drive the grindstone 117 to perform grinding work or cutting work on the workpiece.

  FIG. 2 is a motor control circuit diagram for controlling the drive motor 111. As shown in the figure, a power supply 127 is connected to the controller 121. In addition, the trigger switch 123 is connected to the controller 121 so that the position detection signal of the trigger switch 123 is input as an electrical signal. The controller 121 corresponds to the “control device” in the present invention, and the trigger switch 123 corresponds to the “operation switch” in the present invention. The drive circuit 125 of the drive motor 111 is provided with a semiconductor switch 129 that controls the magnitude of the current flowing through the drive circuit 125. In accordance with a signal from the controller 121, the semiconductor switch 129 has a high current energization state in which a high current is energized, a stop current energization state in which a low current is energized, and a non-energization state in which the energization is interrupted. Are switched to any one state. The semiconductor switch 129 corresponds to the “switch” in the present invention. Further, the high current energization state corresponds to the “first state” in the present invention, the uninterrupted current energization state corresponds to the “second state” in the present invention, and the non-energized state corresponds to the “third state” in the present invention. Corresponding to

  The trigger switch 123 operated by the trigger 115 is in an off state when the trigger 115 is in an initial position not pulled by the user, and the trigger 115 is pulled from the initial position to the operating position by the operator's fingers. When turned on. The controller 121 receives a signal indicating that the trigger switch 123 is turned off (hereinafter referred to as an “off signal”) when the trigger 115 is not operated, and the signal indicating that the trigger switch 123 is turned on (hereinafter referred to as an “on signal”) when the trigger 115 is pulled. Is input).

  The controller 121 controls the semiconductor switch 129 based on the power-on timing of the power supply 127 and the on / off signal of the trigger switch 123 input to the controller 121. That is, when the power supply 127 is turned on while the off signal indicating that the trigger switch 123 is in the off state is input, the controller 121 drives the drive circuit of the drive motor 111 based on the off signal. When the semiconductor switch 129 is operated so that 125 is in a non-energized state and the trigger switch 123 outputs an on signal, the drive circuit 125 of the drive motor 111 is energized at a high current based on the on signal. The semiconductor switch 129 is operated to thereby drive the drive motor 111 at a predetermined high speed.

  Further, when the power supply 127 is turned on while the on signal indicating that the trigger switch 123 is in the on state is input, the controller 121 energizes the drive circuit 125 of the drive motor 111 with a low current. The semiconductor switch 129 is operated so as to be in a state, and the drive motor 111 is configured to be driven at a constant low speed rotation lower than a predetermined high speed rotation.

  FIG. 3 shows an on / off operation of the trigger switch 123, an on / off operation of the power source 127, and an operation example of the drive motor 111 (a relationship between energization and non-energization due to high current or low current). The controller 121 may control the energization / non-energization of the drive motor 111 at a high current and a low current by analog control, microcomputer control, or other control.

  The disc grinder 101 according to the present embodiment is configured as described above, and the operation thereof will be described below. For example, when a power failure occurs when the trigger 115 is pulled to the operation position and is locked to the operation position by the lock-on mechanism (or when the plug of the electric cord is pulled out from the outlet), FIG. As shown, the power supply from the power supply 127 is turned off (cut off) while the trigger switch 123 is locked in the on state. That is, the power supply to the drive motor 111 is cut off while the trigger switch 123 ON signal is input to the controller 121, and the drive motor 111 stops.

  Then, when the power failure is restored with the trigger switch 123 ON signal being output to the controller 121 (or when the electrical cord plug is inserted into the outlet), the power supply is resumed, that is, the power supply 127 is turned on. Therefore, the controller 121 outputs a signal to the semiconductor switch 129 so that a low current is supplied to the drive circuit 125 of the drive motor 111. As a result, a low current is applied to the drive circuit 125 of the drive motor 111, and the drive motor 111 is driven at a low speed rotation lower than a predetermined high speed rotation via the power transmission mechanism (see section A in FIG. 3). For this reason, the grindstone 117, which is the tip tool, is driven by the drive motor 111 at a slow low-speed rotation that is lower (slower) than the normal high-speed rotation. That is, restarting of the drive motor 111 at high speed is prevented. The user can recognize that the trigger switch 123 is locked in the ON state by visually recognizing the driving state of the grindstone 117 at low speed rotation.

  In the above state, if the trigger 115 is unlocked and the trigger switch 123 is returned to the off state, a signal indicating the off state of the trigger switch 123 is output. Therefore, the controller 121, based on the off signal, The semiconductor switch 129 is operated so that the drive circuit 125 of the drive motor 111 is not energized. Thereby, the energization to the drive circuit 125 of the drive motor 111 is cut off, and the drive motor 111 stops. Therefore, when the trigger 115 is subsequently pulled, the trigger switch 123 is turned on again, and the on-state signal is input to the controller 121. Accordingly, the controller 121 outputs a signal to the semiconductor switch 129 so that a high current is supplied to the drive circuit 125 of the drive motor 111. As a result, a high current is applied to the drive circuit 125 of the drive motor 111, and the drive motor 111 is driven at a predetermined high-speed rotation (see part B in FIG. 3).

  If the trigger switch 123 is in an off state when power supply is resumed, that is, when the power supply 127 is turned on, the controller 121 causes the semiconductor switch 129 and the drive circuit 125 of the drive motor 111 to be in a non-energized state based on the signal in the off state. The stop state of the drive motor 111 is maintained. Thereafter, when the trigger 115 is pulled to the operation position, the drive motor 111 is driven at a predetermined high speed as usual.

  As described above, according to the present embodiment, when the power supply 127 is turned on while the trigger switch 123 is locked in the ON state, the drive motor 111 is unexpectedly driven at a predetermined high speed. In addition, it is possible to positively notify the user that the trigger switch 123 (trigger 115) is in the lock-on state by driving the grindstone 117 at a low speed rotation different from the normal time.

  In the above-described embodiment, when the power switch 127 is turned on while the trigger switch 123 is locked to the on state, the trigger switch 123 is locked on by driving the drive motor 111 at a constant low speed. However, the drive motor 111 may be configured to intermittently rotate at a low speed. In other words, the drive circuit 125 of the drive motor 111 may be alternately switched between the energized state and the non-energized state by causing the semiconductor switch 129 to perform an on / off operation at a predetermined interval.

  In addition to the configuration in which the drive motor 111 is rotated at a low speed or the configuration in which the drive motor 111 is intermittently rotated, a sound generator is provided to generate a warning sound such as an emergency bell, a horn or a siren, and trigger the switch 123 to the user. May be configured to notify that there is a lock-on state.

Moreover, although embodiment mentioned above demonstrated in the case of the system which supplies an electric current from the power supply 127 to the drive motor 111 using the electrical cord 119, you may apply to the rechargeable electric tool which uses a battery as a power supply. . In the rechargeable electric tool, when the power is turned on with the trigger switch 123 in the on state, for example, the trigger 115 is kept in the lock on state, the battery is removed and charged, and the charged battery is replaced with the disc grinder. This corresponds to the state in which power feeding is resumed by mounting the battery holder.
In this embodiment, the electric disc grinder is described as an electric tool.However, the electric disc grinder is not limited to the electric disc grinder, and the working tool used for drilling operation and tightening operation, cutting operation, cutting operation, grinding operation, Any electric work tool using a motor as a drive source, such as a work tool used for polishing work, can be widely applied.

1 is a perspective view showing an overall configuration of a hand-held electric disc grinder according to an embodiment of the present invention. It is a control circuit diagram of a drive motor. It is a figure which shows the on / off operation | movement of a trigger switch, the on / off state of a power supply, and the operation example of a drive motor.

Explanation of symbols

101 Electric disc grinder (electric tool)
103 Main Body 105 Motor Housing 107 Gear Housing 109 Main Handle 111 Drive Motor (Motor)
113 Auxiliary handle 115 Trigger 117 Wheel (tip tool)
121 Controller 123 Trigger switch 125 Drive circuit 127 Power supply 129 Semiconductor switch

Claims (4)

A tip tool that performs a predetermined machining operation on the workpiece; and
A motor that rotates at a predetermined rotational speed to drive the tip tool;
Power supply means for supplying current to the motor;
An electric tool having an operation switch that can be switched between an on state for driving the motor and an off state for stopping the motor,
When the power supply means supplies power with the operation switch locked to the ON state, the motor is driven at a rotational speed lower than a predetermined rotational speed, and the tip tool driven by the motor is driven. A power tool that notifies that the operation switch is in an ON state by a low-speed driving state. The electric tool according to claim 1,
A sound generator, and when the power supply means supplies power in a state where the operation switch is locked in an ON state, the sound generator is activated, and in addition to the low-speed drive state of the tip tool An electric tool characterized by notifying that the operation switch is in an ON state also by a sound generated by the sound generator. The electric tool according to claim 1 or 2,
The power tool is configured such that the low-speed driving state of the tip tool is performed as an intermittent operation. The electric tool according to claim 1,
The operation switch is configured to output an electrical signal indicating whether the operation switch is in an on state for driving the motor or an off state for stopping the motor,
A third state provided in the motor drive circuit, the first state in which the drive circuit is energized at a high current, the second state in an energized state at a low current, or the non-energized state A changeover switch that operates to change to one of the states,
A control device that switches and controls the change-over switch to any one of the first state, the second state, and the third state based on an electrical signal output from the operation switch;
The controller is
In a state where an electric signal indicating that the operation switch is in an ON state is input, when the power feeding unit performs power feeding, the changeover switch is operated to the second state and the driving circuit is operated. Is switched to an energized state at a low current, thereby driving the motor at a rotational speed lower than the predetermined rotational speed,
In a state where an electric signal indicating that the operation switch is in the OFF state is input, when the power supply means supplies power, the changeover switch is operated to the third state, and the drive circuit Then, when an electric signal indicating that the operation switch has been switched to the on state is input, the switch is operated to the first state based on the input signal. An electric tool characterized in that a drive circuit is switched to an energized state at a high current, whereby the motor is driven at the predetermined rotational speed.

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