JP2018051678A - Electric power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power tool comprising a striking mechanism, which can enhance convenience in loosening a nut and screws.SOLUTION: The electric power tool comprises a determining part that is configured to determine whether or not a fastened and fixed object is loosened when a motor is driven in a direction of reverse rotation. In the electric power tool, a control part, when the determining part determines that the object is loosened at time t2 after starting to drive the motor in the direction of reverse rotation, stops power supply to the motor for a period of time during which the motor rotates by prescribed rotation amounts, to bring the motor into a free-run state, and then applies a brake to the motor to stop the motor at time t3 at which the period of time ends.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a power tool including a striking mechanism.

  Patent Literature 1 describes a tightening tool including a striking mechanism that intermittently generates instantaneous torque when a hammer collides with an anvil. In the tightening tool described in Patent Document 1, when the motor is driven in the reverse rotation direction, which is the way to loosen the nuts, the motor is stopped after a predetermined time since the collision between the hammer and the anvil is not detected. It is comprised so that rotation may be stopped.

Japanese Patent No. 3660554

  When loosening a nut fastened to a bolt using the tightening tool of Patent Document 1, if the predetermined time is set to a short time, it may be difficult to loosen the nut by hand or tighten the nut. In order to move the desired return amount from the fixed position, it must be turned many times by hand, which takes time. The return amount referred to here is the amount of movement in the loosening direction.

  For this reason, the predetermined time is set to a somewhat long time. If it does so, since it will continue moving a nut toward the front-end | tip of a volt | bolt vigorously even if a hit | damage stops occurring, the following inconvenience arises.

  For example, in the case of a bolt provided with a nut screwed in advance, such as a clamp used to connect a pipe for a scaffold, a process for preventing the nut from dropping off at the tip of the bolt ( Hereinafter, a dropout prevention part) may be provided. When loosening a nut fastened to a bolt having such a drop-off prevention portion, if the nut hits the drop-off prevention portion of the bolt vigorously, the drop-off prevention portion may be damaged. On the other hand, in the case of a bolt that does not have a drop-off prevention portion at the tip, the nut is pulled out from the tip of the bolt vigorously, and as a result, there is a high possibility that the nut will be lost.

  Therefore, one aspect of the present disclosure provides a technique for improving convenience when loosening nuts and screws in an electric tool including a striking mechanism.

The power tool in the first aspect of the present disclosure includes a motor, a striking mechanism, a rotation direction setting unit, an operation unit, a control unit, and a determination unit.
The striking mechanism has an output part to which a tool element is mounted, and rotates the output part by the rotational force of the motor. When a torque of a predetermined value or more is applied to the output part from the outside, the output part is Stroke in the direction of rotation of the output section.

  The rotation direction setting unit sets the rotation direction of the motor to one of a normal rotation direction that is a direction in which the object is tightened by the tool element and a reverse rotation direction that is a direction in which the object is tightened. Operated by the user of the power tool.

The operation unit is operated by the user to instruct driving of the motor.
When the operation unit is operated, the control unit drives the motor in the rotation direction set by the direction setting unit.

The determination unit determines whether or not the object that has been fastened and fixed has been loosened when the motor is driven in the reverse direction.
When the determination unit determines that the object has been loosened after starting to drive the motor in the reverse rotation direction, the control unit stops the power supply to the motor for a predetermined period and puts the motor into a free-run state. After that (ie, when the predetermined period is over), the motor is braked to stop the motor.

  According to such an electric tool, when the object that is fastened and fixed is loosened, the motor is in a free-run state for a predetermined period after the object is loosened, and then the motor is braked.

  For this reason, for example, when loosening a nut fastened to a bolt, even if the nut hits the drop prevention part formed at the tip of the bolt during the predetermined period, the momentum that the nut hits the drop prevention part Get smaller. Therefore, it is suppressed that the fall prevention part in a bolt is damaged. Further, no drop prevention portion is provided at the tip of the bolt, and even if the nut comes off from the tip of the bolt during the predetermined period, the momentum of the nut coming out is reduced. For this reason, possibility that a nut will be lost becomes low. And since the breakage of the drop-off prevention part in the bolt and the loss of the nut can be suppressed, the predetermined period can be set to a long period. Therefore, it is not difficult to loosen the nut by hand, and it is not necessary to turn the nut many times by hand to move the nut from the tightening and fixing position by a desired return amount.

  That is, with this electric power tool, even if the predetermined period is set longer, damage to the drop-off prevention portion of the bolt and the momentum when the nut comes out of the bolt can be reduced. Therefore, it is possible to avoid a shortage of the return amount of the nut by setting the predetermined period longer. Similarly, for example, when loosening a wood screw or the like, it is possible to avoid that the wood screw comes out of the fixing base material vigorously and a desired return amount cannot be obtained.

From the above, according to this electric power tool, convenience when loosening nuts and screws can be enhanced.
In the electric power tool according to the second aspect of the present disclosure, the control unit starts driving the motor in the reverse rotation direction, and then, when the determination unit determines that the object is loosened, the electric power supplied to the motor for a predetermined period. After that, the motor is braked to stop the motor. Even with such a power tool, the same effect as the power tool in the first aspect described above can be obtained.

  In the electric tool according to the third aspect of the present disclosure, the control unit starts driving the motor in the reverse rotation direction and then determines that the object is loosened by the determination unit. A brake having a braking force smaller than the braking force that reaches the stop is applied, and then the motor is stopped by applying a brake having a braking force larger than the braking force in the predetermined period. That is, the control unit applies a weak brake to the motor for a predetermined period, and then applies a strong brake to the motor to stop the motor. Even with such a power tool, the same effects as those of the power tools in the first and second aspects described above can be obtained.

  The determination unit may be configured to determine that the object has loosened when the rotational speed of the motor exceeds a predetermined determination value. This is because it is considered that the rotational speed of the motor continues to increase when the object in the tightened and fixed state is loosened. And if comprised in this way, it will be easy to determine that the target object loosened easily.

  In addition, the determination unit may be configured to determine that the object has been loosened when it is determined that the hit by the hitting mechanism has occurred after the motor has started to be driven in the reverse rotation direction, and then no longer hits. good. This is because it is considered that the hit is not generated when the object in the tightened and fixed state is loosened. In this case, when the determination unit detects a specific phenomenon that appears due to the occurrence of the hit and determines that the phenomenon does not occur within a predetermined determination time, the hit does not occur (that is, the object is loosened). It may be configured to determine.

The predetermined period may be a period during which the motor rotates by a predetermined rotation amount. According to this configuration, it is easy to stabilize the return amount of the object to be loosened.
The predetermined period may be a period until a predetermined waiting time elapses.

  And the time setting part which sets the waiting time based on the rotation speed of a motor or the physical quantity relevant to this rotation speed may be provided in an electric tool. According to such an electric tool, it is easy to stabilize the return amount of the object to be loosened.

  When the determination unit detects a specific phenomenon that appears due to the occurrence of an impact and determines that the phenomenon does not occur within a predetermined determination time, it determines that an impact has not occurred (that is, the object has loosened). When configured as described above, the control unit may be configured as follows.

  That is, the control unit starts measuring the rotation amount of the motor every time the determination unit detects the phenomenon, and after the determination unit determines that no hit occurs, the measured value of the rotation amount is set to a predetermined value. The period until the value is reached may be configured as the predetermined period.

  According to such a configuration, the timing when the rotation amount of the motor after the specific phenomenon appears last becomes the set value can be set as the end timing of the predetermined period. In other words, there will be a delay by the above-mentioned determination time from when the specific phenomenon appears last until it is determined by the determination unit that no impact has occurred, but the amount of rotation of the motor at that determination time is also taken into account. The end timing of the predetermined period can be determined. Therefore, it is easier to stabilize the return amount of the object to be loosened.

  Furthermore, the determination unit may be configured to detect at least a hitting end phenomenon that is a phenomenon appearing at the end of hitting as the specific phenomenon. According to this configuration, the timing at which the amount of rotation of the motor after the end of the last hit becomes the set value can be set as the end timing of the predetermined period. For this reason, it is easier to stabilize the return amount of the object to be loosened.

It is a longitudinal cross-sectional view of the electric tool of embodiment. It is a block diagram showing the electric constitution of a motor drive device. It is a flowchart showing a motor drive process. It is a flowchart showing the auto stop detection process of 1st Embodiment. It is a time chart explaining the effect | action of 1st Embodiment. It is a flowchart showing a hall sensor count process. It is explanatory drawing explaining the effect | action of 1st Embodiment. It is a flowchart showing the auto stop detection process of 2nd Embodiment. It is a time chart explaining the effect | action of 2nd Embodiment. It is a flowchart showing the auto stop detection process of 3rd Embodiment. It is a flowchart showing a time measuring process. It is a time chart explaining the effect | action of 3rd Embodiment. It is a flowchart showing the auto stop detection process of 4th Embodiment. It is a time chart explaining the effect | action of 4th Embodiment. It is a flowchart showing the auto stop detection process of 5th Embodiment. It is a time chart explaining the effect | action of 5th Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Overall configuration of power tool]
The electric tool 1 of this embodiment shown in FIG. 1 is configured as a rechargeable impact wrench. In the description of the electric power tool 1, the vertical direction is the vertical direction in FIG. 1, the rear side is the left side in FIG. 1, and the front side is the right side in FIG.

As shown in FIG. 1, the electric tool 1 includes a tool body 10 and a battery pack 30 that supplies power to the tool body 10.
The tool body 10 includes a housing 2 in which the motor 4 and the striking mechanism 6 are housed, and a grip portion 3 formed so as to protrude from the lower portion of the housing 2.

  A motor 4 is housed in the rear portion of the housing 2, and a bell-shaped hammer case 5 is assembled in front of the motor 4. An impact mechanism 6 is accommodated in the hammer case 5.

  A spindle 7 having a hollow portion formed on the rear end side is coaxially accommodated in the hammer case 5, and a ball bearing 8 provided on the rear end side in the hammer case 5 is provided at the rear end of the spindle 7. It supports the outer periphery. A planetary gear mechanism 9 including two planetary gears that are axially supported in a point-symmetric manner with respect to the rotation axis is formed on the inner peripheral surface of the rear end side of the hammer case 5 at the front portion of the ball bearing 8 in the spindle 7. The internal gear 11 is engaged. The planetary gear mechanism 9 meshes with a pinion 13 formed at the tip of the output shaft 12 of the motor 4. The output shaft 12 is fixed coaxially with the rotor 4 a of the motor 4.

  The striking mechanism 6 includes a spindle 7, a hammer 14 mounted on the spindle 7, an anvil 15 that is pivotally supported on the front side of the hammer 14, and a coil spring 16 that biases the hammer 14 forward. The

The hammer 14 is connected to the spindle 7 so as to be integrally rotatable and movable in the axial direction, and is urged forward (ie, on the anvil 15 side) by a coil spring 16.
The tip of the spindle 7 is rotatably supported by being coaxially inserted into the rear end of the anvil 15. The anvil 15 receives the rotational force and striking force of the hammer 14 and rotates around the axis. The anvil 15 is supported by a bearing 20 provided at the tip of the housing 2 so as to be rotatable about the axis and not displaceable in the axial direction. ing. A mounting portion 19 for mounting a socket as a tool element for rotating an object such as a bolt or a nut is formed at the tip of the anvil 15. The socket is not shown.

The output shaft 12, the spindle 7, the hammer 14, the anvil 15 and the mounting portion 19 of the anvil 15 of the motor 4 are all arranged so as to be coaxial.
Further, on the front end surface of the hammer 14, two striking projections 17 and 17 for giving a striking force to the anvil 15 are projected at an interval of 180 ° in the circumferential direction. On the other hand, on the rear end side of the anvil 15, two striking arms 18 and 18 configured so that the striking protrusions 17 and 17 of the hammer 14 can come into contact with each other are formed at an interval of 180 ° in the circumferential direction. ing.

  The hammer 14 is urged and held on the front end side of the spindle 7 by the urging force of the coil spring 16, so that the hitting projections 17 and 17 of the hammer 14 come into contact with the hitting arms 18 and 18 of the anvil 15. It becomes like this.

  In this state, when the spindle 7 is rotated via the planetary gear mechanism 9 by the rotational force of the motor 4, the hammer 14 is rotated together with the spindle 7, and the rotational force of the hammer 14 is applied to the striking protrusions 17 and 17 and the striking arm 18, 18 to the anvil 15. As a result, the socket mounted on the mounting portion 19 at the tip of the anvil 15 rotates.

  When the rotation direction of the motor 4 is the forward rotation direction in which the bolt or nut that is the object is tightened, the object can be tightened by the socket. In the present embodiment, the forward rotation direction is a clockwise direction when viewed from the rear end side of the electric power tool 1. Moreover, when the rotation direction of the motor 4 is the reverse rotation direction opposite to the normal rotation direction, the object can be tightened by the socket.

  In both the forward and reverse rotations of the motor 4, if a torque of a predetermined value or more is applied to the anvil 15 from the outside in the direction opposite to the rotation direction of the motor 4, the rotational force of the hammer 14 against the anvil 15 (Torque) also becomes a predetermined value or more. As a result, the hammer 14 is displaced rearward against the urging force of the coil spring 16, and the striking protrusions 17, 17 of the hammer 14 get over the striking arms 18, 18 of the anvil 15. That is, the hitting projections 17 and 17 of the hammer 14 are temporarily detached from the hitting arms 18 and 18 of the anvil 15 and are idled. The forward rotation of the motor 4 is when the motor 4 is driven in the forward rotation direction, and the reverse rotation of the motor 4 is when the motor 4 is driven in the reverse rotation direction.

  When the striking protrusions 17 and 17 of the hammer 14 get over the striking arms 18 and 18 of the anvil 15 in this way, the hammer 14 is displaced forward again by the urging force of the coil spring 16 while rotating together with the spindle 7. 14 hitting projections 17 and 17 hit the hitting arms 18 and 18 of the anvil 15 in the rotation direction.

  Therefore, in the electric power tool 1, every time a torque of a predetermined value or more is applied to the anvil 15, the hammer 14 is repeatedly hit by the hammer 14. The hammer 14 is intermittently applied to the anvil 15 so that the bolts and nuts, which are the objects, can be fastened with high torque when the motor 4 is rotating forward, and the objects are rotated when the motor 4 is reversed. Can be loosened.

The grip portion 3 is a portion that is gripped when an operator uses the electric power tool 1.
A trigger switch 21 is provided above the grip portion 3. The trigger switch 21 is turned on / off by a trigger 21a that is pulled by an operator, and a pulling operation of the trigger 21a, and a resistance value changes according to an operation amount (that is, a pulling amount) of the trigger 21a. A switch body 21b configured as described above.

  Further, on the upper side of the trigger switch 21 (that is, on the lower end side of the housing 2), a forward / reverse selector switch operated by the user to set the rotation direction of the motor 4 to either the forward rotation direction or the reverse rotation direction. 22 is provided.

Further, an illumination LED 23 is provided in front of the lower portion of the housing 2 for irradiating the front of the electric tool 1 with light when the trigger 21a is pulled.
In addition, a setting unit 24 for setting an operation mode and the like of the electric tool 1 is provided below the grip unit 3. The setting unit 24 indicates to the user whether the mode changeover switch 54 shown in FIG. 2 for setting the validity / invalidity of the reverse rotation automatic stop function or whether the reverse rotation automatic stop function is set to valid or invalid. For this purpose, a mode LED 55 shown in FIG. 2 is provided. The reverse rotation automatic stop function is a function for automatically stopping the motor 4 when the motor 4 rotates in reverse.

  On the other hand, a battery pack 30 containing a battery 29 is detachably attached to the lower end of the grip portion 3. The battery pack 30 is attached by sliding the battery pack 30 from the front side to the rear side with respect to the lower end of the grip portion 3. The battery 29 accommodated in the battery pack 30 is a rechargeable secondary battery such as a lithium ion secondary battery.

  In this embodiment, the motor 4 is constituted by a three-phase brushless motor provided with armature windings of U, V, and W phases. The motor 4 is provided with a hall sensor 56 shown in FIG. 2 as a sensor for detecting the rotational position and rotational speed of the motor 4. The rotation position and rotation speed of the motor 4 are specifically the rotation position and rotation speed of the rotor 4a in the motor 4.

  The hall sensor 56 is a rotational position sensor including a hall element as a magnetoelectric conversion element. The Hall sensor 56 outputs position detection signals (hereinafter referred to as Hall sensor signals) Hu, Hv, and Hw for each phase of U, V, and W based on the change in the magnetic field accompanying the rotation of the rotor 4a. In the present embodiment, the hall sensor signals Hu, Hv, and Hw are switched between high and low every time the rotor 4a rotates 180 degrees in electrical angle. Then, the phase of each Hall sensor signal Hu, Hv, Hw is shifted by 120 ° in electrical angle. For this reason, every time the rotor 4a rotates 60 degrees in electrical angle, a level change edge occurs in any of the Hall sensor signals Hu, Hv, Hw. The level change edge includes both a rising edge from low to high and a falling edge from high to low. Hereinafter, the level change edge is simply referred to as an edge. The hall sensor signals Hu, Hv, and Hw are collectively referred to as the hall sensor signal H.

A motor driving device 40 shown in FIG. 2 is provided inside the grip portion 3 and receives power supply from the battery pack 30 to drive and control the motor 4.
[1-2. Configuration of motor drive unit]
As shown in FIG. 2, the motor drive device 40 includes a drive circuit 42, a gate circuit 44, a control circuit 46, and a regulator 48.

  The drive circuit 42 is for receiving power supply from the battery 29 and causing a current to flow through each phase winding of the motor 4. In the present embodiment, the drive circuit 42 is a three-phase full bridge circuit including six switching elements Q1 to Q6. It is configured as. The switching elements Q1 to Q6 are MOSFETs in the present embodiment, but may be other types of switching elements such as bipolar transistors.

  In the drive circuit 42, the three switching elements Q <b> 1 to Q <b> 3 are provided as so-called high side switches between the terminals U, V, W of the motor 4 and the power supply line connected to the positive side of the battery 29. Yes. The other three switching elements Q4 to Q6 are provided as so-called low-side switches between the terminals U, V, and W of the motor 4 and the ground line connected to the negative electrode side of the battery 29.

  The gate circuit 44 supplies current to each phase winding of the motor 4 by turning on / off the switching elements Q1 to Q6 in the drive circuit 42 according to the control signal output from the control circuit 46. It is intended to rotate.

  The control circuit 46 is configured by a microcomputer (hereinafter referred to as a microcomputer) mainly including a CPU, a ROM, a RAM, and the like. The function of the control circuit 46 is realized by the CPU of the microcomputer executing a program stored in a non-transitional tangible recording medium. In this example, the ROM corresponds to a non-transitional tangible recording medium that stores a program. Further, by executing this program, a method corresponding to the program is executed. The number of microcomputers constituting the control circuit 46 may be plural. Further, the method of realizing the function of the control circuit 46 is not limited to software, and part or all of the function may be realized using hardware combining a logic circuit, an analog circuit, and the like.

  The control circuit 46 is connected to the above-described trigger switch 21 (specifically, the switch body 21b), the forward / reverse selector switch 22, the illumination LED 23, the mode selector switch 54, and the mode LED 55.

  The motor driving device 40 is also provided with a battery voltage detection unit 52 that detects a supply voltage (that is, a battery voltage) from the battery 29. The control circuit 46 also receives a detection signal from the battery voltage detection unit 52.

  Further, in the motor drive device 40, a current detection circuit 54 that detects the current that flows to the motor 4 is provided in the energization path from the drive circuit 42 to the negative electrode side of the battery 29. The current detection signal from the current detection circuit 54 is also input to the control circuit 46.

  The control circuit 46 performs a process of setting the rotation direction when driving the motor 4 to either the normal rotation direction or the reverse rotation direction in accordance with the rotation direction setting signal from the forward / reverse selector switch 22. When the trigger switch 21 is operated, the control circuit 46 obtains the rotational position and rotational speed of the motor 4 based on the Hall sensor signal H from the Hall sensor 56, and sets the motor 4 in accordance with the rotational direction setting signal. Drive in the direction of rotation.

  Further, the control circuit 46 sets the speed command value of the motor 4 according to the operation amount of the trigger switch 21 when the motor 4 is driven. The control circuit 46 sets the drive duty ratio of each of the switching elements Q1 to Q6 constituting the drive circuit 42 according to the speed command value, and outputs a control signal corresponding to the drive duty ratio to the gate circuit 44. The rotational speed of the motor 4 is controlled.

  In addition to the control process for driving the motor, the control circuit 46 enables, for example, a process for setting valid / invalid of the reverse rotation auto stop function according to the on / off state of the mode switch 54 and the reverse rotation auto stop function. In such a case, processing for turning on the mode LED 55 is executed. The control circuit 46 also executes processing for turning on the illumination LED 23 when the motor is driven.

  On the other hand, the regulator 48 receives power supply from the battery 29 and generates a constant power supply voltage Vcc (for example, DC 5V) necessary for operating the control circuit 46. The control circuit 46 operates when the power supply voltage Vcc is supplied from the regulator 48.

[1-3. Explanation of processing]
[1-3-1. Motor drive processing]
Next, among various processes executed by the control circuit 46, the motor drive process executed by the control circuit 46 when the rotation direction of the motor 4 is set to the reverse rotation direction by the forward / reverse selector switch 22. Will be described with reference to FIG. That is, the motor driving process of FIG. 3 is a process executed when the motor 4 is rotated in the reverse rotation direction and, for example, a bolt or a nut is loosened by a socket mounted on the mounting unit 19. And this motor drive processing is performed for every fixed time, for example.

As shown in FIG. 3, when the motor drive process is started, the control circuit 46 determines whether or not the trigger switch 21 is operated by the user and is turned on in S110.
If it is determined that the trigger switch 21 is on, the control circuit 46 determines whether or not the brake command flag is set in S120 and determines that the brake command flag is not set. If so, the process proceeds to S130. The brake command flag is a flag that means that the motor 4 is immediately stopped, and is set in an auto-stop detection process described later. Setting a flag means setting the value of the flag to “1”, for example. Conversely, clearing a flag means setting the value of the flag to “0”, for example.

  In S130, the control circuit 46 determines whether or not the reverse rotation auto stop flag is set. If it is determined that the reverse rotation auto stop flag is not set, the control circuit 46 proceeds to S140. The reverse auto stop flag is a flag that means that an auto stop operation (that is, an automatic stop operation) during reverse rotation of the motor 4 is performed, and is set in an auto stop detection process described later.

  In S140, the control circuit 46 sets the speed command value (that is, the target rotation speed) of the motor 4 according to the operation amount of the trigger switch 21, and the switching elements Q1 to Q6 in the drive circuit 42 according to the speed command value. Calculate the drive duty ratio. In step S150, the control circuit 46 outputs the control signal corresponding to the drive duty ratio calculated in step S140 to the gate circuit 44, thereby driving the motor 4. The greater the drive duty ratio calculated in S140, the greater the power supplied to the motor 4 and the greater the output of the motor 4. And the control circuit 46 complete | finishes the said motor drive process, after performing the process of S150.

  Therefore, when the trigger switch 21 is in the ON state and both the brake command flag and the reverse rotation auto stop flag are not set, the motor 4 is driven according to the operation amount of the trigger switch 21.

  If the control circuit 46 determines in S130 that the reverse rotation auto stop flag is set, the process proceeds to S160. In S160, the control circuit 46 stops the power supply to the motor 4 and puts the motor 4 into a free-run state. Specifically, all the switching elements Q1 to Q6 in the drive circuit 42 are turned off. And the control circuit 46 complete | finishes the said motor drive process, after performing the process of S160.

  If the control circuit 46 determines in S120 that the brake command flag is set, the control circuit 46 proceeds to S170. In S <b> 170, the control circuit 46 performs brake control for braking the motor 4 in order to stop the motor 4. Specifically, on / off of the switching elements Q1 to Q6 in the drive circuit 42 is controlled so that the motor 4 functions as a generator. And the control circuit 46 complete | finishes the said motor drive process, after performing the process of S170.

  On the other hand, when the control circuit 46 determines in S110 that the trigger switch 21 is not in the on state (that is, in the off state), the control circuit 46 proceeds to S170. In this case, the control circuit 46 also performs processing for clearing the brake command flag and the reverse rotation automatic stop flag.

[1-3-2. Auto stop detection process]
In the control circuit 46, the rotation direction of the motor 4 is set to the reverse rotation direction by the forward / reverse selector switch 22, the reverse rotation automatic stop function is set to be effective by the mode switch 54, and the trigger switch 21 is turned on. In the case of the state, the automatic stop detection process of FIG. 4 is performed. That is, the control circuit 46 performs the auto stop detection process of FIG. 4 when the reverse rotation auto stop function is set to be effective and the motor 4 is driven in the reverse rotation direction. This auto-stop detection process is executed, for example, in the form of multitasking in parallel with the motor drive process of FIG.

  As shown in FIG. 4, when the auto-stop detection process is started, the control circuit 46 increases or decreases the motor rotation speed within a predetermined start determination time T1 from the start of the motor 4 (ie, at the start of driving) in S210. Whether or not has occurred is determined. The motor rotation speed is the rotation speed of the motor 4. An increase / decrease change is both a change from increase to decrease and a change from decrease to increase. Hereinafter, the increase / decrease change in the motor rotation speed is also simply referred to as a speed increase / decrease change.

  Specifically, in S210, the control circuit 46 performs a process of monitoring the motor rotation speed to detect a speed increase / decrease change (that is, a process of detecting an extreme value of the motor rotation speed), and the speed increase / decrease change is It is determined whether or not the motor 4 is detected within the activation determination time T1 from the activation. In S210, as a speed increase / decrease change, as shown at time t1 in FIG. 5, only a change from an increase in motor rotation speed to a decrease (that is, a maximum value) may be detected.

If the control circuit 46 determines in S210 that the speed increase / decrease change has occurred within the activation determination time T1 from the activation of the motor 4, the process proceeds to S220.
In S220, the control circuit 46 determines whether or not a speed increase / decrease change has occurred within a predetermined determination time T2 from the previous detection of the speed increase / decrease change. Specifically, in S220, the control circuit 46 performs a process of detecting a speed increase / decrease change, and determines whether or not the speed increase / decrease change is detected within the determination time T2 from the previous detection.

  When the control circuit 46 determines in S220 that the speed increase / decrease change has occurred within the determination time T2, the control circuit 46 performs the determination in S220 again. Therefore, as shown in the period from time t1 to time t2 in FIG. 5, if the speed increase / decrease change (that is, the extreme value of the motor rotation speed) repeatedly appears within the determination time T2, the control circuit 46 determines in S220. The process will be repeated.

  Further, if the control circuit 46 determines in S220 that the speed increase / decrease change does not occur within the determination time T2, that is, if the speed increase / decrease change does not occur even after the determination time T2 is exceeded, the batting is performed. It is determined that the hit by the mechanism 6 has not occurred, and the process proceeds to S230. The hit in this embodiment is a hit on the anvil 15 by the hammer 14.

  In S230, the control circuit 46 determines that the object that has been tightened and fixed (that is, the object to be loosened) has been loosened, and sets the reverse rotation automatic stop flag. Then, the control circuit 46 starts a hall sensor count process for counting the edges of the hall sensor signal H in the next S240.

  The hall sensor count process is executed as an interrupt process that is started every time an edge occurs in the hall sensor signal H, for example. Then, as shown in FIG. 6, in the hall sensor count process, the control circuit 46 increments the hall sensor count value, which is the count value of the edge of the hall sensor signal H, in S300, and then the hall sensor count process. Exit. For this reason, the control circuit 46 specifically permits the start of the hall sensor count process in S240 of FIG. Further, for example, when it is determined in S110 of FIG. 3 that the trigger switch 21 is in the OFF state, the Hall sensor count value is cleared and the start of the Hall sensor count process is prohibited.

  Returning to FIG. 4, the control circuit 46 determines whether or not the Hall sensor count value has reached the predetermined set value Ns in S <b> 250 and waits until the Hall sensor count value reaches the set value Ns. If the control circuit 46 determines in S250 that the Hall sensor count value has reached the set value Ns, the process proceeds to S260. The control circuit 46 also proceeds to S260 when it is determined in S210 that the speed increase / decrease change has not occurred within the activation determination time T1 from the activation of the motor 4.

In S260, the control circuit 46 sets a brake command flag, and then ends the auto-stop detection process.
[1-4. Example of action]
As shown in the upper part (A) of FIG. 7, the operation of the electric power tool 1 will be described by taking as an example a case where the nut 65 fastened to the bolt 63 protruding from the base 61 such as a wall or a metal plate is loosened. To do. In the example of FIG. 7, a drop prevention portion 63 a for preventing the nut 65 from dropping off is formed at the tip of the bolt 63.

  When loosening the nut 65 in the state shown in the upper part (A) of FIG. 7, the user of the electric tool 1 sets the rotation direction of the motor 4 to the reverse rotation direction by the forward / reverse selector switch 22. Furthermore, it is assumed that the user has enabled the reverse rotation automatic stop function by the mode changeover switch 54. Then, the user only has to engage the socket 65 mounted on the mounting portion 19 with the nut 65 and pull the trigger switch 21 in this state.

Then, the drive of the motor 4 is started by the control circuit 46 performing the processing of S140 and S150 in FIG.
Since the nut 65 is fastened and fixed, as soon as the drive of the motor 4 is started, the first striking by the striking mechanism 6 occurs immediately, and thereafter, as shown in the middle stage (B) of FIG. Strikes occur repeatedly until 65 is loosened. In the middle part (B) of FIG. 7, in order to make it easy to understand that the nut 65 has been loosened, the interval between the nut 65 and the base member 61 at the point in time when no impact is generated is shown larger than the actual distance. .

  Here, as shown in the period from time t1 to time t2 in FIG. 5, the increase / decrease change of the motor rotation speed repeatedly occurs during the period in which the impact is repeatedly generated. In other words, the maximum value and the minimum value of the motor rotation speed are continuously generated in time series.

  That is, when the striking projections 17 and 17 of the hammer 14 hit the striking arms 18 and 18 of the anvil 15 and start to get over the striking arms 18 and 18 (that is, at the start of one striking), the motor rotation speed Is a local maximum. Thereafter, when the striking protrusions 17 and 17 get over the striking arms 18 and 18 (that is, at the end of one striking), the motor rotation speed becomes a minimum value. When the striking protrusions 17 and 17 that have passed over the striking arms 18 and 18 strike the striking arms 18 and 18 again (that is, at the start of the next striking), the motor rotation speed becomes the maximum value again. Such an operation is repeated.

  The above-described activation determination time T1 is a time slightly longer than an assumed value of the time from when the motor 4 is activated until the motor rotation speed first reaches the maximum value (that is, the time until the first strike starts) ( For example, 100 ms) is set. The assumed value is a value assumed in design. Further, the above-described determination time T2 is a time (for example, 50 ms) slightly longer than an assumed value of a time interval at which an extreme value appears in the motor rotation speed when the hit is repeated (that is, a time interval at which a speed increase / decrease change occurs). Is set.

  For this reason, as shown at time t1 in FIG. 5, within the start determination time T1 from the start of the motor 4, the motor rotation speed changes from increase to decrease as an increase / decrease change indicating the first strike (ie, Local maximum) occurs. Then, during repeated hitting, as shown in the period from time t1 to time t2 in FIG. 5, the motor rotational speed is changed or increased (that is, extreme value) within the determination time T2. .

  Therefore, the control circuit 46 determines “YES” in S210 of FIG. 4 within the activation determination time T1 after starting the driving of the motor 4. The determination of “YES” in S210 by the control circuit 46 corresponds to the detection of the first hit. After that, while the hit is repeatedly generated, the control circuit 46 repeatedly determines “YES” in S220 of FIG. At this time, since neither the reverse rotation auto-stop flag nor the brake command flag is set, the control circuit 46 repeatedly executes the processes of S140 and S150 in FIG. 3 to drive the motor 4.

Thereafter, as shown in the middle part (B) of FIG. 7, the nut 65 is loosened and no impact is generated.
Then, as shown at time t2 in FIG. 5, when the time during which the speed increase / decrease change does not occur exceeds the determination time T2, the control circuit 46 determines “NO” in S220 of FIG. 4, and in S230 of FIG. The object (that is, the nut 65 in this example) is determined to be loose, and the reverse rotation automatic stop flag is set. Further, the control circuit 46 starts counting the edges of the Hall sensor signal H in S240 of FIG.

  When the reverse rotation automatic stop flag is set, the control circuit 46 does not execute the processes of S140 and S150 in FIG. 3, but instead executes the process of S160 in FIG. 3 to put the motor 4 in a free-run state. . For this reason, the nut 65 moves to the right in FIG. 7 from the position shown in the middle (B) of FIG. 7 by inertial rotation of the motor 4.

  Then, as shown at time t3 in FIG. 5, when the Hall sensor count value, which is the count value of the edge of the Hall sensor signal H, reaches the set value Ns, the control circuit 46 determines “YES” in S250 of FIG. Then, the brake command flag is set in S260 of FIG.

  When the brake command flag is set, the control circuit 46 does not execute the process of S160 in FIG. 3, but instead executes the process of S170 in FIG. 3 to perform the brake control for braking the motor 4. As a result, the motor 4 is stopped.

  Then, the set value Ns to be compared with the Hall sensor count value is set so that the brake control is started before the nut 65 reaches the drop-off preventing portion 63a of the bolt 63 as shown in the lower part (C) of FIG. The value is set to stop the motor 4.

  The control circuit 46 is configured to variably set each of the activation determination time T1 and the determination time T2 according to, for example, both or one of the battery voltage as the power supply voltage and the trigger operation amount. May be. The trigger operation amount is the operation amount of the trigger switch 21. For example, the control circuit 46 sets each of the activation determination time T1 and the determination time T2 to a smaller (that is, shorter) value as the battery voltage increases, and to a larger (or longer) value as the trigger operation amount increases. It can be constituted as follows. The control circuit 46 is configured to variably set each of the activation determination time T1 and the determination time T2 using a calculation formula or a data map using both or one of the battery voltage and the trigger operation amount as a parameter. be able to.

  Further, the control circuit 46 also variably sets the set value Ns to be compared with the Hall sensor count value in accordance with, for example, an operation of a setting switch by a user or a command from an external device such as a personal computer. It may be configured.

[1-5. effect]
The power tool 1 according to the first embodiment as described above has the following effects.
(1a) When the control circuit 46 starts to drive the motor 4 in the reverse rotation direction and determines “NO” in S220 of FIG. 4, that is, when it is determined that no impact occurs, the control circuit 46 determines that the object has loosened. Then, the counting of the edges of the Hall sensor signal H is started. Then, the control circuit 46 stops the power supply to the motor 4 for a predetermined period from this point in time (that is, until the Hall sensor count value reaches the set value Ns), and puts the motor 4 into a free-run state. Thereafter, the motor 4 is braked to stop the motor 4.

  In other words, if the control circuit 46 determines that the object has been loosened, it waits for a predetermined period and then brakes the motor 4. In particular, the control circuit 46 does not continue to drive the motor 4 during a waiting period from when it is determined that the object has been loosened until the brake is applied to the motor 4 (hereinafter referred to as a brake waiting period). ing.

  Therefore, for example, when the power tool 1 is used to loosen the nut 65 shown in FIG. 7, for example, the set value Ns is set to a large value, and in the brake waiting period in which the motor 4 is brought into the free-run state, the nut Even if 65 hits the drop prevention part 63a of the bolt 63, the momentum at which the nut 65 hits the drop prevention part 63a is reduced. For this reason, it is suppressed that the drop-off prevention part 63a is damaged. Further, the bolt 63 is not provided with the drop-off preventing portion 63a, and even when the nut 65 is pulled out from the tip end of the bolt 63 during the brake waiting period, the momentum at which the nut 65 is pulled out becomes small. For this reason, possibility that the nut 65 will be lost becomes low.

  And since the breakage prevention part 63a can be prevented from being damaged and the nut 65 is lost, the set value Ns can be set larger, and the brake waiting period can be set to a longer period. Accordingly, it is not difficult to loosen the nut 65 by hand, and it is not necessary to turn the nut 65 by hand to move the nut 65 from the tightening and fixing position by a desired return amount.

  That is, with this electric power tool, even if the brake waiting period is set longer, damage to the drop-off prevention unit 63a and momentum when the nut 65 comes out of the bolt 63 can be reduced. Therefore, it is possible to avoid a shortage of the return amount of the nut 65 by setting a longer brake waiting period. Similarly, for example, when loosening a wood screw or the like, it is possible to avoid that the wood screw comes out of the fixing base material vigorously and a desired return amount cannot be obtained.

From the above, according to the electric power tool 1, the convenience when loosening nuts and screws can be enhanced.
(1b) The brake waiting period is a period until the hall sensor count value reaches the set value Ns, that is, a period during which the motor 4 rotates by a set rotation amount determined by the set value Ns. For this reason, it is easy to stabilize the return amount of the object to be loosened. In the present embodiment, the set rotation amount is “60 ° × set value Ns” in terms of electrical angle. The electrical angle of 60 ° is an edge generation interval in the Hall sensor signal H.

  (1c) When the control circuit 46 determines that no impact occurs after starting to drive the motor 4 in the reverse rotation direction, the control circuit 46 determines that the object is loosened. For this reason, it is possible to increase the determination accuracy that the object is loose. Then, when the control circuit 46 determines that the speed increase / decrease change as a specific phenomenon that appears due to the occurrence of the hit does not occur within the determination time T2, the control circuit 46 determines that no hit occurs. For this reason, it is possible to correctly determine that no impact has occurred.

  Further, since the speed increase / decrease change is detected as a specific phenomenon, it is possible to determine that the hit is not generated without providing a special sensor such as a vibration sensor or a sound sensor for detecting the hit.

  As a comparative example, for example, an impact detection sensor such as a vibration sensor or a sound sensor is provided in the electric tool 1, and the control circuit 46 determines that an impact has occurred when the output value of the impact detection sensor exceeds a predetermined value. You may comprise so that it may do. In this case, the control circuit 46 is configured such that, when it is determined that the phenomenon that the output value of the hit detection sensor is equal to or greater than the predetermined value does not occur within the determination time T2, it is determined that no hit occurs. be able to. However, in the case of this comparison, an impact detection sensor is required.

  In the first embodiment, the anvil 15 corresponds to an output unit in the striking mechanism 6, the forward / reverse selector switch 22 corresponds to a rotation direction setting unit, and the trigger switch 21 corresponds to an operation unit. The control circuit 46 corresponds to a control unit. The control circuit 46 also corresponds to a determination unit. That is, the control circuit 46 also functions as a determination unit. And S210, S220, S230 in Drawing 4 is equivalent to processing as a judgment part.

[2. Second Embodiment]
Since the basic configuration of the second embodiment is the same as that of the first embodiment, differences will be described below. In addition, as a code | symbol of an electric tool, the same "1" as 1st Embodiment is used. In addition to the reference numeral “1”, the same reference numerals as those in the first embodiment indicate the same configurations and processes as those in the first embodiment, and the preceding description is referred to. These also apply to other embodiments described later.

[2-1. Difference from the first embodiment]
In the electric power tool 1 of the second embodiment, as compared with the first embodiment, the control circuit 46 performs the auto stop detection process of FIG. 8 instead of the auto stop detection process of FIG.

The auto-stop detection process in FIG. 8 differs from the auto-stop detection process in FIG. 4 in the following [2-1-1] and [2-1-2].
[2-1-1]
S240 is deleted, and S215 is provided instead. When it is determined “YES” in S210, the control circuit 46 proceeds to S215, and in S215, performs the same process as S240, that is, a process of starting the hall sensor count process. Then, the process proceeds to S220.

[2-1-2]
S225 is added. When it is determined “YES” in S220, the control circuit 46 proceeds to S225 and resets the Hall sensor count value to zero. Thereafter, the determination in S220 is performed again. When the Hall sensor count value is reset in S225, the edge count of the Hall sensor signal H is started (that is, restarted) from the beginning.

[2-2. effect]
According to the electric tool 1 of the second embodiment as described above, in addition to the effects described in the first embodiment, the following effects can be obtained.

  Since the control circuit 46 performs the processes of S215 and S225 in FIG. 8, the Hall sensor signal H is detected every time a change in speed that appears due to the occurrence of a hit is detected, as shown in the period from time t1 to time t2 in FIG. The edge counting (that is, the measurement of the rotation amount of the motor 4) is started from the beginning.

  For this reason, the brake waiting period is a period from when it is determined that the object is loosened in S230 of FIG. 8 (that is, time t2 of FIG. 9) until the Hall sensor count value reaches the set value Ns. However, the count start timing of the Hall sensor count value is the time when the speed increase / decrease change accompanying the impact occurs last (that is, time te in FIG. 9). Therefore, the timing at which the rotation amount of the motor 4 from the time when the speed increase / decrease change associated with the hit last becomes the set rotation amount can be set as the end timing of the brake waiting period.

  That is, after the speed increase / decrease change appears lastly, it is delayed by the determination time T2 until it is determined that the object has loosened (that is, it is determined that the hit is not generated), but the determination time T2 In consideration of the amount of rotation of the motor 4 (that is, the amount of rotation from time te to time t2 in FIG. 9), the end timing of the brake waiting period can be determined. Therefore, it is easier to stabilize the return amount of the object to be loosened.

  Further, the control circuit 46 detects at least a change from a decrease to an increase as a speed increase / decrease change that appears due to the occurrence of an impact. A change from a decrease in motor rotation speed to an increase (that is, a minimum value) corresponds to a striking end phenomenon that appears at the end of a single striking. For this reason, the count of the edge of the Hall sensor signal H is started from the beginning at least at the end of each hit.

  Therefore, the timing at which the rotation amount of the motor 4 has reached the set rotation amount from when the last hit is completed (that is, when the object is loosened by the hit) can be set as the end timing of the brake waiting period. For this reason, it is easier to stabilize the return amount of the object to be loosened. Note that the speed increase / decrease change detected by the control circuit 46 may be only one of a change from increase to decrease and a change from decrease to increase, but at least a change from decrease to increase is detected. By comprising, it becomes easy to stabilize the return amount of a target object.

[3. Third Embodiment]
[3-1. Difference from the first embodiment]
In the electric power tool 1 of the third embodiment, as compared with the first embodiment, the control circuit 46 performs the auto stop detection process of FIG. 10 instead of the auto stop detection process of FIG.

The auto stop detection process of FIG. 10 is provided with S235, S245, and S255 instead of S240 and S250 as compared with the auto stop detection process of FIG.
As shown in FIG. 10, in the auto stop detection process, the control circuit 46 performs the process of S230 and then proceeds to S235.

  In S235, the control circuit 46 calculates the waiting time Tw, which is the length of the brake waiting period, based on the current motor rotation speed (ie, when it is determined that the object has been loosened). Then, the calculated waiting time Tw is set as a determination value used for determination in S255 described later.

  Specifically, the control circuit 46 is a calculation formula for calculating the waiting time Tw from the motor rotation speed, and a calculation in which the calculated value of the waiting time Tw becomes smaller (that is, shorter) as the motor rotation speed increases. It has an expression. And the control circuit 46 calculates the waiting time Tw by detecting a motor rotational speed and substituting the detected value for the said calculation formula. This calculation formula may be a formula in which the waiting time Tw is inversely proportional to the motor rotation speed. Further, the control circuit 46 may calculate the waiting time Tw by using a data map representing the correspondence relationship between the motor rotation speed and the waiting time Tw.

  The motor rotation speed can be detected from a time interval when an edge occurs in the Hall sensor signal. The motor rotation speed used to calculate the waiting time TW may be detected when it is determined “NO” in S220.

  As a modification, in S235, the control circuit 46 estimates the current motor rotation speed from the physical quantity related to the motor rotation speed, such as the current battery voltage and the drive duty ratio, and uses the estimated value, It may be configured to calculate the waiting time Tw.

  As another modification, the control circuit 46 may calculate the waiting time Tw based on the physical quantity instead of the detected value or estimated value of the motor rotation speed in S235. For example, the control circuit 46 uses a calculation formula or a data map that is set so that the calculated value of the waiting time Tw becomes smaller as the battery voltage is larger and the driving duty ratio is larger. Can be configured to calculate. The physical quantity used to calculate the waiting time Tw may be both the battery voltage and the driving duty ratio, or one of them. Further, other physical quantities may be added.

After performing the process of S235, the control circuit 46 proceeds to S245 and starts a time measurement process for measuring time.
Note that the timing process is executed as a timer interrupt process that is started at regular intervals, for example. Then, as shown in FIG. 11, in the time measurement process, the control circuit 46 increments the timer value corresponding to the time measurement value in S310, and then ends the time measurement process. For this reason, the control circuit 46 specifically permits the start of the time measurement process in S245 of FIG. Further, for example, when it is determined in S110 of FIG. 3 that the trigger switch 21 is in the OFF state, the timer value is cleared and the start of the timing process is prohibited.

  Returning to FIG. 10, in the next S255, the control circuit 46 determines whether or not the measured value of the time when the measurement is started in S245 has reached the waiting time Tw set in S235. Specifically, it is determined whether or not the timer value counted up in the time measurement process has reached a value corresponding to the waiting time Tw. The value corresponding to the waiting time Tw is a value obtained by dividing the waiting time Tw by the execution period of the time measurement process.

  Then, in S255, the control circuit 46 waits until it is determined that the time measurement value has reached the waiting time Tw. If it is determined that the time measurement value has reached the waiting time Tw, the control circuit 46 proceeds to S260, where the brake command flag Set.

The control circuit 46 does not execute the hall sensor count process of FIG.
In such a third embodiment, as shown at time t2 in FIG. 12, when the control circuit 46 determines that the time when the speed increase / decrease change does not occur exceeds the determination time T2 and the object is loosened, 4 is set to a free-run state and time measurement is started. When the time measurement value reaches the waiting time Tw, the motor 4 is braked and stopped as shown at time t3 in FIG.

[3-2. effect]
In the electric power tool 1 of the third embodiment, the brake waiting period is a period until the waiting time Tw elapses. For this reason, the brake waiting period can be managed by time. Therefore, it is not necessary to perform processing for counting the edges of the Hall sensor signal H.

  Further, the control circuit 46 sets the waiting time Tw based on the motor rotation speed or a physical quantity (for example, battery voltage or drive duty ratio) related to the motor rotation speed. For this reason, it is easy to stabilize the return amount of the object to be loosened.

  In the third embodiment, the control circuit 46 also corresponds to a time setting unit. That is, the control circuit 46 also functions as a time setting unit. And S235 in FIG. 10 is equivalent to the process as a time setting part.

[4. Fourth Embodiment]
[4-1. Difference from the third embodiment]
The power tool 1 of the fourth embodiment is different from the third embodiment in that the control circuit 46 detects an impact based on a current (hereinafter, motor current) that has flowed through the motor 4.

  As shown in the period from time t1 to time t2 in FIG. 14, the motor current increases and decreases repeatedly during the period in which the impact is repeatedly generated. In other words, the minimum value and the maximum value of the motor current are continuously generated in time series. That is, the motor current becomes a minimum value at the start of one hit. Thereafter, at the end of one hit, the motor current reaches a maximum value. Then, at the start of the next hit, the motor current becomes the minimum value again. Such an operation is repeated. In FIG. 14, the time t1 at which the motor current first reaches the minimum value is the start timing of the first impact, but the maximum value of the motor current occurring before the time t1 is due to the impact. Instead, it is a local maximum due to the inrush current at the start of energization. In the following, the increase / decrease change in motor current is also simply referred to as current increase / decrease change.

For this reason, the control circuit 46 performs the auto stop detection process of FIG. 13 instead of the auto stop detection process of FIG.
The auto stop detection process of FIG. 13 is provided with S410 and S420 instead of S210 and S220 as compared with the auto stop detection process of FIG.

  As shown in FIG. 13, when the control circuit 46 starts the auto-stop detection process, in S410, the change from the decrease to the increase among the current increase / decrease changes within the above-described start determination time T1 from the start of the motor 4. It is determined whether or not (that is, the minimum value of the motor current) has occurred.

  Specifically, in S410, the control circuit 46 monitors the motor current, performs a process of detecting a change from a decrease in the motor current to an increase, and determines the change from the decrease to the increase when the motor 4 is started. It is determined whether or not it is detected within the activation determination time T1.

  If the control circuit 46 determines in S410 that a change from a decrease in motor current to an increase has occurred within the start determination time T1 from the start of the motor 4, the process proceeds to S420. If the control circuit 46 determines in S410 that no change from a decrease in motor current to an increase has occurred within the start determination time T1 from the start of the motor 4, the process proceeds to S260 described above.

  In S420, the control circuit 46 determines whether or not a current increase / decrease change has occurred within the aforementioned determination time T2 from the previous detection of the current increase / decrease change. The previous detection of the current increase / decrease change includes the time when “YES” is determined in S410, that is, the time when the change from decrease in motor current to increase is detected in S410.

  Specifically, in S420, the control circuit 46 performs a process of monitoring the motor current and detecting a current increase / decrease change (that is, a process of detecting an extreme value of the motor current), It is determined whether or not it is detected within the determination time T2 from the time of detection.

  When the control circuit 46 determines in S420 that the current increase / decrease change has occurred within the determination time T2, the control circuit 46 performs the determination in S420 again. Therefore, as shown in the period from time t1 to time t2 in FIG. 14, if the current increase / decrease change (that is, the extreme value of the motor current) repeatedly appears within the determination time T2, the control circuit 46 performs the process of S420. Will be repeated.

  If the control circuit 46 determines in S420 that the current increase / decrease change does not occur within the determination time T2, that is, if the current increase / decrease change does not occur even after the determination time T2 is exceeded, the control circuit 46 Is determined not to occur, and the process proceeds to S230. In S230, it is determined that the object has been loosened, and a reverse rotation auto stop flag is set.

[4-2. effect]
As shown at time t2 in FIG. 14, the control circuit 46 determines that the object has loosened when the time during which no current increase or decrease occurs exceeds the determination time T2, puts the motor 4 in a free-run state, Start measuring time. Then, when the measured time value reaches the waiting time Tw, the motor 4 is braked to stop the motor 4 as shown at time t3 in FIG. According to the fourth embodiment, the same effect as that of the third embodiment can be obtained.

  Moreover, the detection of the impact based on the motor current can be applied to each of the first to third embodiments. In that case, the processes of S210 and S220 in FIGS. 4, 8, and 10 may be replaced with the processes of S410 and S420 in FIG.

  In the fourth embodiment, S410, S420, and S230 in FIG. 13 correspond to processing as a determination unit. The speed increase / decrease change corresponds to a phenomenon to be detected that appears due to the occurrence of a hit. Moreover, even if S210 and S220 in FIG. 8 are replaced with S410 and S420 in FIG. 13, the same effects as those of the second embodiment can be obtained. This is because in S420, as a current increase / decrease change that appears due to the occurrence of a hit, at least a change from an increase to a decrease (that is, a maximum value) is detected as a hit end phenomenon.

[5. Fifth Embodiment]
[5-1. Difference from the first embodiment]
In the electric power tool 1 of the fifth embodiment, as compared with the first embodiment, the control circuit 46 performs the auto stop detection process of FIG. 15 instead of the auto stop detection process of FIG.

The auto stop detection process of FIG. 15 is provided with S510 instead of S210 and S220 as compared with the auto stop detection process of FIG.
As shown in FIG. 15, when the automatic stop detection process is started, the control circuit 46 determines whether or not the motor rotation speed exceeds a predetermined looseness determination value in S510, and the motor rotation speed exceeds the looseness determination value. Wait until. If the control circuit 46 determines in S510 that the motor rotation speed has exceeded the looseness determination value, the control circuit 46 proceeds to S230, determines that the object has been loosened, and sets the reverse rotation automatic stop flag. The subsequent processing is the same as in the first embodiment.

  That is, as shown at time t2 in FIG. 16, the control circuit 46 determines that the object has relaxed when the motor rotation speed exceeds the looseness determination value, and starts counting the edges of the Hall sensor signal H. At the same time, the motor 4 is brought into a free-running state. Then, as shown at time t <b> 3 in FIG. 16, when the Hall sensor count value reaches the set value Ns, the control circuit 46 brakes the motor 4 and stops the motor 4.

  In addition, as shown before the time t2 in FIG. 16, if the target object which was in the tightening and fixing state is loosened by the impact, it is considered that the motor rotation speed continues to increase. For this reason, the looseness determination value is set to a value at which the motor rotation speed reaches when the object is loosened. In FIG. 16, the “loosening detection period” until time t <b> 2 is a period from when driving in the reverse direction of the motor 4 is started until it is determined that the object is loosened.

  In addition, the control circuit 46 may be configured to variably set the looseness determination value according to, for example, both or one of the battery voltage and the trigger operation amount. For example, the control circuit 46 can be configured to set the looseness determination value to a larger value as the battery voltage is larger and the trigger operation amount is larger. The control circuit 46 can be configured to variably set the looseness determination value using a calculation formula or a data map using both or one of the battery voltage and the trigger operation amount as a parameter.

[5-2. effect]
The power tool 1 of the fifth embodiment as described above also has the same effects as the above (1a) and (1b) described for the first embodiment. Further, the control circuit 46 of the fifth embodiment determines that the object has been loosened when the rotational speed of the motor exceeds the looseness judgment value. For this reason, it can be easily determined that the object is loose, and high determination accuracy can be obtained.

In the fifth embodiment, S510 and S230 in FIG. 15 correspond to processing as a determination unit.
Further, the processing of S510 in FIG. 15 can also be applied to the third embodiment. That is, the processing of S210 and S220 in FIG. 10 may be replaced with the processing of S510 in FIG.

[6. Sixth Embodiment]
In each of the first to fifth embodiments, the control circuit 46 may set the output to the motor 4 to a low duty output in S160 of FIG. 3, as described in () in FIG. . The low duty output is to output a control signal corresponding to a driving duty ratio smaller than the driving duty ratio calculated in S140 to the gate circuit 44. Specifically, the switching elements Q1 to Q6 are driven with the small drive duty ratio, and the power supplied to the motor 4 is reduced as compared with the case where the processes of S140 and S150 are executed. .

  When configured in this way, the control circuit 46 lowers the power supplied to the motor 4 during the brake waiting period than before the brake waiting period, and then brakes the motor 4.

The sixth embodiment also provides the same effects as those described for the first to fifth embodiments.
[7. Seventh Embodiment]
In each of the first to fifth embodiments, the control circuit 46 may apply a loose brake to the motor 4 in S160 of FIG. 3 as described in {} in FIG. The loose brake is a brake that is looser than the brake applied to the motor 4 in S170 of FIG. 3 and has a braking force smaller than the braking force that causes the motor 4 to stop.

  In such a configuration, the control circuit 46 applies a weak brake to the motor 4 during the brake waiting period, and then applies a strong brake to the motor 4 to stop the motor 4.

The seventh embodiment can provide the same effects as those described for the first to fifth embodiments.
[8. Other Embodiments]
As mentioned above, although embodiment of this indication was described, this indication can take various forms, without being limited to the above-mentioned embodiment. The above-mentioned numerical values are also examples, and other values may be used.

  For example, in S210 and S220 of the auto-stop detection process in the first to third embodiments, the motor rotation speed is equal to or higher than a threshold value Rth (for example, 4000 rpm or higher), as indicated by a one-dot chain line in FIGS. It is also possible to detect a change in speed. Similarly, in S410 and S420 of the auto stop detection process in the fourth embodiment, as shown by the alternate long and short dash line in FIG. 14, the current increase / decrease change is detected on condition that the motor current is equal to or greater than the threshold value Ith. May be. The threshold values Rth and Ith can be set to the lowest value when an effective hit occurs, for example. If comprised in this way, the detection accuracy of a hit | damage and the detection accuracy that the hit | damage did not generate | occur | produce can be raised.

  In S220 of the automatic stop detection process in the first to third embodiments, as shown by the two-dot chain line in FIGS. 5, 9, and 12, a difference of a predetermined value ΔR or more from the extreme value of the speed increase / decrease change detected last time. The speed increase / decrease change that has a certain extreme value may be detected. Similarly, in S420 of the auto-stop detection process in the fourth embodiment, as indicated by a two-dot chain line in FIG. 14, the current increase / decrease that becomes an extreme value having a difference of a predetermined value ΔI or more from the extreme value of the current increase / decrease change detected last time. Changes may be detected. The predetermined values ΔR and ΔI can be set to, for example, the minimum values when an effective hit occurs. If comprised in this way, the detection accuracy of a hit | damage and the detection accuracy that the hit | damage did not generate | occur | produce can be raised.

  The striking mechanism is not limited to a hammer that strikes the anvil. For example, using a hydraulic pressure generated by the relative rotation of the case and the spindle, the striking mechanism may strike the spindle as an output unit. A so-called oil unit configured may be used. The striking of the striking mechanism to the output unit can be said to be instantaneous torque. Such an oil unit is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-289596, Japanese Patent Application Laid-Open No. 2005-219139, Japanese Patent Application Laid-Open No. 2002-59371, and the like.

  The power tool is not limited to a rechargeable impact wrench, and may be any tool provided with a striking mechanism driven by a motor, such as an impact driver. Moreover, although the motor 4 was demonstrated as what is comprised with a three-phase brushless motor, what is necessary is just a motor which can drive a striking mechanism. Moreover, the power tool is not limited to a rechargeable type, and may be one that receives power supply via a cord.

  A plurality of functions of one constituent element in the embodiment may be realized by a plurality of constituent elements, or a single function of one constituent element may be realized by a plurality of constituent elements. Further, a plurality of functions possessed by a plurality of constituent elements may be realized by one constituent element, or a single function realized by a plurality of constituent elements may be realized by one constituent element. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  In addition to the above-described power tool, a system including the power tool as a constituent element, a program for causing a computer to function as the power tool, a non-transitory actual recording medium such as a semiconductor memory storing the program, a power tool The present disclosure can also be realized in various forms such as a motor control method.

  DESCRIPTION OF SYMBOLS 1 ... Electric tool, 2 ... Housing, 3 ... Grip part, 4 ... Motor, 4a ... Rotor, 5 ... Hammer case, 6 ... Impact mechanism, 7 ... Spindle, 8 ... Ball bearing, 9 ... Planetary gear mechanism, 10 ... Tool 11 ... Internal gear, 12 ... Output shaft, 13 ... Pinion, 14 ... Hammer, 15 ... Anvil, 16 ... Coil spring, 17 ... Blowing protrusion, 18 ... Blowing arm, 19 ... Mounting part, 20 ... Bearing, 21 Trigger switch, 21a Trigger, 21b Switch body part, 22 Forward / reverse selector switch, 23 Lighting LED, 24 Setting unit, 29 Battery, 30 Battery pack, 40 Motor drive device, 42 Drive circuit , 44 ... Gate circuit, 46 ... Control circuit, 48 ... Regulator, 52 ... Battery voltage detection unit, 54 ... Mode changeover switch, 54 ... Current detection circuit, 55 ... Mode De LED, 56 ... Hall sensor, 61 ... base, 63 ... Bolt, 63a ... disengagement prevention part, 65 ... nut, Q1 to Q6 ... switching element

Claims (11)

A motor,
An output unit on which a tool element is mounted; when the output unit is rotated by the rotational force of the motor, and when a torque of a predetermined value or more is applied to the output unit from the outside, the output unit A striking mechanism configured to strike the rotating direction of the output section;
In order to set the rotation direction of the motor to one of a normal rotation direction that is a direction of tightening the object by the tool element and a reverse rotation direction that is a direction of loosening the tightening of the object, A rotation direction setting unit configured to be operated by a user;
An operation unit configured to be operated by the user to instruct driving of the motor;
A control unit configured to drive the motor in a rotation direction set by the direction setting unit when the operation unit is operated;
A determination unit configured to determine whether or not the object that has been tightened and fixed has been loosened when the motor is driven in the reverse rotation direction; and
The controller is
When the determination unit determines that the object has been loosened after starting to drive the motor in the reverse rotation direction, the power supply to the motor is stopped for a predetermined period of time, and the motor is set to a free-run state. And then configured to brake the motor and stop the motor.
Electric tool. A motor,
An output unit on which a tool element is mounted; when the output unit is rotated by the rotational force of the motor, and when a torque of a predetermined value or more is applied to the output unit from the outside, the output unit A striking mechanism configured to strike the rotating direction of the output section;
In order to set the rotation direction of the motor to one of a normal rotation direction that is a direction of tightening the object by the tool element and a reverse rotation direction that is a direction of loosening the tightening of the object, A rotation direction setting unit configured to be operated by a user;
An operation unit configured to be operated by the user to instruct driving of the motor;
A control unit configured to drive the motor in a rotation direction set by the direction setting unit when the operation unit is operated;
A determination unit configured to determine whether or not the object that has been tightened and fixed has been loosened when the motor is driven in the reverse rotation direction; and
The controller is
When the determination unit determines that the object has been loosened after starting to drive the motor in the reverse rotation direction, the power supplied to the motor is reduced for a predetermined period, and then the brake is applied to the motor. Configured to stop the motor over time,
Electric tool. A motor,
An output unit on which a tool element is mounted; when the output unit is rotated by the rotational force of the motor, and when a torque of a predetermined value or more is applied to the output unit from the outside, the output unit A striking mechanism configured to strike the rotating direction of the output section;
In order to set the rotation direction of the motor to one of a normal rotation direction that is a direction of tightening the object by the tool element and a reverse rotation direction that is a direction of loosening the tightening of the object, A rotation direction setting unit configured to be operated by a user;
An operation unit configured to be operated by the user to instruct driving of the motor;
A control unit configured to drive the motor in a rotation direction set by the direction setting unit when the operation unit is operated;
A determination unit configured to determine whether or not the object that has been tightened and fixed has been loosened when the motor is driven in the reverse rotation direction; and
The controller is
When the determination unit determines that the object has been loosened after starting to drive the motor in the reverse rotation direction, the motor has a braking force smaller than the braking force that causes the motor to stop for a predetermined period. The brake is applied, and then the motor is stopped by applying a brake having a braking force larger than the braking force in the predetermined period to the motor.
Electric tool. The power tool according to any one of claims 1 to 3,
The determination unit
When the rotational speed of the motor exceeds a predetermined determination value, it is configured to determine that the object is loosened.
Electric tool. The power tool according to any one of claims 1 to 3,
The determination unit
It is configured to determine that the object has been loosened when it is determined that the impact has occurred after the motor has started to be driven in the reverse rotation direction, and then the impact has ceased to occur.
Electric tool. The power tool according to claim 5,
The determination unit
It is configured to detect a specific phenomenon that appears due to the occurrence of the hit, and to determine that the hit no longer occurs when it is determined that the phenomenon does not occur within a predetermined determination time.
Electric tool. The power tool according to any one of claims 1 to 6,
The predetermined period is a period during which the motor rotates by a predetermined rotation amount.
Electric tool. The power tool according to any one of claims 1 to 6,
The predetermined period is a period until a predetermined waiting time elapses.
Electric tool. The power tool according to claim 8,
A time setting unit configured to set the waiting time based on a rotation speed of the motor or a physical quantity related to the rotation speed;
Electric tool. The electric tool according to claim 6,
The controller is
Each time the determination unit detects the phenomenon, measurement of the rotation amount of the motor is started. After the determination unit determines that the hit is not generated, the measured value of the rotation amount becomes a predetermined set value. The period until reaching the predetermined period is configured,
Electric tool. The electric tool according to claim 10,
The determination unit
As the specific phenomenon, it is configured to detect at least a hitting end phenomenon that is a phenomenon appearing at the end of the hitting,
Electric tool.