JP5561535B2 - Electric tool - Google Patents

Description

  The present invention relates to an electric tool, and more particularly to an electronic pulse driver that outputs a rotational driving force.

  In a conventional electric power tool, a structure in which an anvil is hit in a certain direction by a hammer rotating in a certain direction is known (see, for example, Patent Document 1).

JP 2008-307664 A

  On the other hand, the applicant of the present invention has newly developed an electronic pulse driver configured to strike an anvil by rotating the hammer forward and backward. In the electronic pulse driver, in order to prevent the fastener from being fastened with excessive torque due to the collision between the hammer and the anvil, the motor is rotated at a low speed to perform the pre-start control to contact the hammer and the anvil. Yes.

  However, in the electronic pulse driver, since the pre-start control is performed for a predetermined time, the pre-start control is performed even when the pre-start is not necessary, for example, when the hammer and the anvil are already in contact. As a result, there was a dead time before the worker started work.

  In addition, after fastening the fastener with the electronic pulse driver, it may not be possible to loosen the fastener with the same torque setting. This is because the static friction coefficient is larger than the dynamic friction coefficient of the fastener. As a result, the operator needs to change the torque setting value, and the workability has deteriorated. SUMMARY OF THE INVENTION An object of the present invention is to provide an electric tool that reduces dead time before work and has excellent workability.

In order to achieve the above object, an electric power tool of the present invention includes a motor that supplies a driving force, a hammer that is rotated in the forward rotation direction or the reverse rotation direction by the driving force, and the forward rotation direction or the reverse rotation direction. An anvil that is struck by the hammer, and the rotational speed of the hammer immediately before the hammer rotated in the reverse rotation direction contacts the anvil is rotated in the forward rotation direction. Further, there is provided an electric tool characterized in that the hammer has a rotational speed greater than that of the hammer immediately before coming into contact with the anvil.

According to such a configuration, even if the set value of the torque of the electric tool is the same when the bolt is tightened and when the bolt is loosened, the bolt can be loosened. After that, the operator can loosen the bolt without changing the torque set value.

In addition, the power supply unit further includes a power supply unit that supplies driving power to the motor, and the power supply unit is configured to rotate the hammer in the reverse rotation direction rather than rotating the hammer in the normal rotation direction at the start of supply. However, it is preferable to supply a large driving power to the motor. The power supply unit further includes a power supply unit that supplies driving power to the motor, and the power supply unit is rotated in the reverse rotation direction until the hammer rotated in the forward rotation direction contacts the anvil. It is preferable to supply a large driving power to the motor until the hammer comes into contact with the anvil. Further, the power supply unit PWMs the motor until the hammer rotated in the reverse rotation direction contacts the anvil rather than the hammer rotated in the forward rotation direction contacts the anvil. It is preferable to supply driving power having a large total duty. In addition, the rotation angle of the hammer rotated in the reverse rotation direction before the contact with the anvil is larger than the rotation angle of the hammer rotated in the normal rotation direction before the contact with the anvil. preferable.

Further, when the hammer is rotated in the forward rotation direction, a pre-start is performed in which the hammer is brought into contact with the anvil with a force that does not rotate the anvil, and when the hammer is rotated in the reverse rotation direction, the pre-start is performed. It is preferable not to perform.

According to such a configuration, when the bolt is loosened, the soft start is performed without performing the pre-start control, so that it is possible to reduce the extra time required for the transition to the operation of loosening the bolt.

  According to the power tool of the present invention, it is possible to provide a power tool that has reduced dead time before work and is excellent in workability.

Sectional drawing of the electronic pulse driver which concerns on the 1st Embodiment of this invention FIG. 3 is an assembly diagram showing the periphery of the gear mechanism of the electronic pulse driver according to the first embodiment of the present invention. The perspective view showing the fan of the electronic pulse driver concerning a 1st embodiment of the present invention. 1 is a control block diagram of an electronic pulse driver according to the first embodiment of the present invention. The figure explaining the control in the drill mode of the electronic pulse driver which concerns on the 1st Embodiment of this invention The figure explaining the control at the time of fastening a fastener in the clutch mode of the electronic pulse driver which concerns on the 1st Embodiment of this invention. The figure explaining the difference in the control by the positional relationship of the hammer and anvil in the clutch mode of the electronic pulse driver which concerns on the 1st Embodiment of this invention. The figure explaining the difference in the control at the time of forward rotation and reverse rotation of the hammer of the electronic pulse driver concerning the 1st embodiment of the present invention. The figure explaining the control at the time of fastening a fastener in the pulse mode of the electronic pulse driver which concerns on the 1st Embodiment of this invention The figure explaining the control at the time of fastening a drill screw in pulse mode of the electronic pulse driver concerning a 2nd embodiment of the present invention. The figure showing the positional relationship of a drill screw and an iron plate at the time of fastening a drill screw in the pulse mode of the electronic pulse driver which concerns on the 2nd Embodiment of this invention. The figure showing the state of a fastener at the time of fastening a fastener in the clutch mode of the electronic pulse driver concerning the modification of the present invention

  Hereinafter, the structure of the electronic pulse driver 1 which is an example of the electric tool which concerns on the 1st Embodiment of this invention is demonstrated based on FIGS. 1-4.

  As shown in FIG. 1, the electronic pulse driver 1 includes a housing 2, a motor 3, a hammer part 4, an anvil part 5, an inverter circuit 6, a control part 7, and a rotational position detection element (Hall element) 8. (Fig. 4). The housing 2 is made of resin and forms an outer shell of the electronic pulse driver 1, and is mainly composed of a substantially cylindrical body portion 21 and a handle portion 22 extending from the body portion 21.

  In the body portion 21, the motor 3 is arranged so that the longitudinal direction thereof coincides with the axial direction of the motor 3, and the hammer portion 4 and the anvil portion 5 are arranged side by side toward one end side in the axial direction of the motor 3. Has been. In the following description, the anvil portion 5 side is defined as the front side, the motor 3 side is defined as the rear side, and a direction parallel to the axial direction of the motor 3 is defined as the front-rear direction. Further, the body part 21 side is defined as the upper side, the handle part 22 side is defined as the lower side, and the direction in which the handle part 22 extends from the body part 21 is defined as the vertical direction. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

  A metal hammer case 23 in which the hammer part 4 and the anvil part 5 are incorporated is arranged at a front side position in the body part 21. The hammer case 23 has a substantially funnel shape in which the diameter gradually decreases toward the front, an opening 23a is formed at the front end portion, and a metal 23A is provided on the inner wall that defines the opening 23a. .

  A light 2 </ b> A for irradiating a bit mounted on a tip tool mounting portion 51, which will be described later, is disposed near the opening 23 a and below the hammer case 23. A dial 2B for mode switching and tightening torque setting, which will be described later, is disposed below the light 2A so as to be rotatable. The light 2 </ b> A and the dial 2 </ b> B are disposed at substantially the center position of the body portion 21 in the left-right direction. The body portion 21 is formed with an inlet and an exhaust port (not shown) through which outside air is sucked and discharged into the body portion 21 by a fan 32 described later. Furthermore, a display unit 26 that displays which mode is selected from a drill mode, a clutch mode, and a pulse mode, which will be described later, is disposed above and behind the body unit 21.

  The handle portion 22 extends downward from a substantially central position in the front-rear direction of the body portion 21 and is configured integrally with the body portion 21. Inside the handle portion 22, a switch mechanism 6 is incorporated, and a battery 24 for supplying electric power to the motor 3 and the like is detachably mounted at a lower end position thereof. A trigger 25 is provided above the handle portion 22 and at the front side position.

  As shown in FIG. 1, the motor 3 is a brushless motor mainly composed of a rotor 3 </ b> A having an output shaft portion 31 and a stator 3 </ b> B arranged to face the rotor 3 </ b> A, and the axial direction of the output shaft portion 31 is It arrange | positions in the trunk | drum 21 so that it may correspond with the front-back direction. The output shaft portion 31 protrudes forward and backward of the rotor 3A, and is rotatably supported on the body portion 21 by a bearing at the protruding portion. A fan 32 that rotates coaxially and integrally with the output shaft portion 31 is provided at a location protruding to the front side of the output shaft portion 31. Further, a pinion gear 31A is connected to the output shaft portion 31 at the foremost end position of the location. It is provided so as to rotate coaxially.

  The hammer part 4 is mainly composed of a gear mechanism 41 and a hammer 42, and is built in the front side of the motor 3 in the hammer case 23. The gear mechanism 41 is a two-stage planetary gear mechanism and includes outer gears 41A and 41B, three planetary gears 41C and 41D, and carriers 41E and 41F, respectively, as shown in FIG. The outer gears 41 </ b> A and 41 </ b> B are fixed in the hammer case 23.

  The first stage planetary gear mechanism will be described. The three planetary gears 41C are arranged around the pinion gear 31A as a sun gear so as to mesh with the pinion gear 31A, and are arranged inside the outer gear 41A so as to mesh with the outer gear 41A. The three planetary gears 41C are fixed to a carrier 41E having a sun gear. With such a configuration, as the pinion gear 31A rotates, the three planetary gears 41B revolve around the pinion gear 31A, and the rotation reduced by the revolution is transmitted to the sun gear of the carrier 41E. Similarly, in the second stage planetary gear mechanism, the rotation of the motor 3 is decelerated and transmitted to the hammer 42.

  The hammer 42 is disposed on the front side of the gear mechanism 41, has a first engagement protrusion 42A and a second engagement protrusion 42B that are disposed opposite to the rotation shaft and project toward the front side ( FIG. 3).

  The anvil portion 5 is disposed in front of the hammer portion 4 and mainly includes a tip tool mounting portion 51 and an anvil 52. The tip tool mounting portion 51 is formed in a cylindrical shape and is rotatably supported in the opening 23a of the hammer case 23 via a metal 23A. A drill 51a into which a bit (not shown) is inserted is drilled in the front tool mounting portion 51 in the front-rear direction, and a chuck 51A for holding a bit (not shown) is provided at the front end portion.

  The anvil 52 is configured to be integrated with the tip tool mounting portion 51 in the hammer case 23 at the rear of the tip tool mounting portion 51, and disposed opposite to the rotation center of the tip tool mounting portion 51. It has the 1st to-be-engaged protrusion 52A and the 2nd to-be-engaged protrusion 52B which protruded toward. When the hammer 42 rotates, the first engagement protrusion 42A and the first engagement protrusion 52A collide with each other, and at the same time, the second engagement protrusion 42B and the second engagement protrusion 52B collide with each other. A rotational force is transmitted to the anvil 52.

Here, the energy K possessed by the rotary body is expressed by the K = Iω ^2/2. For this reason, when the motor 3 and the hammer 42 are decelerated by the gear mechanism 41, the rotational speed of the motor 3 can be made larger than the rotational speed of the hammer 42. Therefore, in order to increase the rotational energy K is, by greater than a rotation moment I _m of the motor 3 to the torque I _h of the hammer 42 may be a compact power tool. Therefore, in the present embodiment, as shown in FIG. 3, a substantially ring-shaped weight 32A is provided on the periphery of the rear outer peripheral surface of the fan 32 to increase the weight and diameter of the rotor 3A, and the moment of inertia on the motor 3 side is increased. I _m is set to be larger than the inertia moment I _h of the hammer 42. In the present embodiment, the diameter D of the rotor 3A is set to 22 mm, and the diameter d of the hammer 42 is set to 45 mm. Further, the front-rear direction by setting the front-rear direction of the length L (37.1mm) long in the rotor 3A than the length I (26.6 mm), the hammer inertia moment _{I m} of the motor 3 side of the hammer 42 It is made larger than 42 of the moment of inertia _{I h.} Specifically, the inertia moment _{I m} of the motor 3 side to ^{5.8 × 10 -6 kg · m 2} , the rotational speed of the motor 3 to 0~17000rpm, 1.1 × moment of inertia _{I h} of the hammer 42 10 < ^-5 > kg * m < ² > and the rotation speed of the hammer 42 are set to 0-1100 rpm.

The ratio of the moment of inertia required at the time of working in the drill mode, which will be described later, is I _m : I _h = 118: 1, and the ratio of the moment of inertia required at the time of working in the pulse mode is I _m. : I _h = 10: 1. Therefore, by reducing the size of the hammer 42 within a range that satisfies these ratios, the entire electronic pulse driver 1 can be reduced in size.

  As shown in FIG. 4, the inverter circuit 6 includes six switching elements Q1 to Q6 such as FETs connected in a three-phase bridge format.

  The control unit 7 is mounted on a substrate disposed near the battery 24 in the handle unit 22, is connected to the battery 24, and is connected to the light 2 </ b> A, the dial 2 </ b> B, the trigger 25, the switching substrate 63, and the display unit 26. It is connected to the. The control unit 7 also includes a current detection circuit 71, a switch operation detection circuit 72, an applied voltage setting circuit 73, a rotation direction setting circuit 74, a rotor position detection circuit 75, a rotation speed detection circuit 76, and an impact. An impact detection circuit 77, a calculation unit 78, and a control signal output circuit 79 are provided.

  The rotational position detecting element 8 is provided at a position facing the permanent magnet 3C of the rotor 3A, and is arranged at predetermined intervals (for example, every angle of 60 °) in the circumferential direction of the rotor 3A.

  Next, the configuration of the drive control system of the motor 3 will be described with reference to FIG. In the present embodiment, the motor 3 is a three-phase brushless DC motor, the rotor 3A has permanent magnets including a plurality of sets (two sets in the present embodiment) N poles and S poles, and the stator 3B is Star-connected three-phase stator windings U, V, and W.

  The gates of the switching elements Q1 to Q6 of the inverter circuit 6 are connected to the control signal output circuit 79 of the control unit 7, and the drains or sources of the switching elements Q1 to Q6 are the stator windings U, V, Connected to W. The six switching elements Q <b> 1 to Q <b> 6 perform a switching operation according to the switching element drive signal input from the control signal output circuit 79, and the DC voltage of the battery 24 applied to the inverter circuit 66 is three-phase (U phase, V phase). And W phase) Electric power is supplied to the stator windings U, V, W as voltages Vu, Vv, Vw. Specifically, the stator windings U, V, and W that are energized by the output switching signals H1, H2, and H3 input from the control signal output circuit 79 to the positive power supply side switching elements Q1, Q2, and Q3, that is, the rotor The direction of rotation of 3A is controlled. Further, power is supplied to the stator windings U, V, and W by pulse width modulation signals (PWM signals) H4, H5, and H6 that are input from the control signal output circuit 79 to the negative power supply side switching elements Q4, Q5, and Q6. The amount, that is, the rotational speed of the rotor 3A is controlled.

  The current detection circuit 71 detects the current value supplied to the motor 3 and outputs it to the calculation unit 78. The switch operation detection circuit 72 detects the presence / absence of the operation of the trigger 25 and outputs it to the calculation unit 78. The applied voltage setting circuit 73 outputs a signal corresponding to the operation amount of the trigger 25 to the calculation unit 78.

  Further, the electronic pulse driver 1 is provided with a forward / reverse switching lever (not shown) for switching the rotation direction of the motor 3. When the rotation direction setting circuit 74 detects switching of the forward / reverse switching lever, the motor 3. A signal for switching the rotation direction is transmitted to the calculation unit 78.

  The rotor position detection circuit 75 detects the rotational position of the rotor 3 </ b> A based on the signal from the rotational position detection element 8 and outputs the detected rotational position to the calculation unit 78. The rotation speed detection circuit 76 detects the rotation speed of the rotor 3 </ b> A based on the signal from the rotation position detection element 8 and outputs the rotation speed to the calculation unit 78.

  Further, the electronic pulse driver 1 is provided with a hitting impact detection sensor for detecting the magnitude of the impact generated in the anvil 52, and the hitting impact detection circuit 77 sends a signal from the hitting impact detection sensor to the calculation unit 78. Output.

Although not shown, the calculation unit 78 is a central processing unit (CPU) for outputting a drive signal based on the processing program and data, a ROM for storing the processing program and control data, and temporary storage of data. RAM and a timer are provided. The calculation unit 78 outputs the output switching signals H1, H2, and H3 based on the signals from the rotation direction setting circuit 74 and the rotor position detection circuit 75, and the pulse width modulation signal (PWM signal) based on the signal from the applied voltage setting circuit 73. ) H4, H5, and H6 are generated and output to the control signal output circuit 79.
The PWM signal may be output to the positive power supply side switching elements Q1 to Q3, and the output switching signal may be output to the negative power supply side switching elements Q4 to Q6.

  Next, operation modes that can be used in the electronic pulse driver 1 according to the first embodiment will be described with reference to FIGS. The electronic pulse driver according to the present embodiment has three operation modes of a drill mode, a clutch mode, and a pulse mode, and the mode can be switched by operating the dial 2B.

  The drill mode is a mode in which the hammer 42 and the anvil 52 are integrally rotated, and is mainly used when wood screws are fastened. As shown in FIG. 5, the current flowing through the motor 3 increases as the fastening proceeds.

  In the clutch mode, as shown in FIG. 6, the driving of the motor 3 is stopped when the current flowing through the motor 3 increases to the target value (target torque) while the hammer 42 and the anvil 52 are rotated together. This mode is mainly used in cases where importance is attached to fastening with an accurate torque, such as fastening fasteners that appear on the exterior after fastening.

  In the pulse mode, as shown in FIG. 9, when the current flowing through the motor 3 is increased to a predetermined value (predetermined torque) while the hammer 42 and the anvil 52 are integrally rotated, This is a mode in which reverse rotation is alternately switched and a fastener is fastened by striking, and is mainly used for fastening a long screw used in a place that does not appear on the appearance. Thereby, a strong fastening force can be supplied, and at the same time, a repulsive force from the workpiece can be reduced.

  Next, the control by the control unit 7 when the electronic pulse driver according to the present embodiment performs the fastening operation will be described. The drill mode will not be described because no special control is performed. In the following description, the start-up current is not considered in the determination based on the current. The start-up current can be avoided by providing a dead time of about 20 ms, for example.

  First, control when the operation mode is set to the clutch mode and the fastener is fastened (during normal rotation of the hammer 42) will be described with reference to FIGS.

  FIG. 6 is a diagram for explaining control when fastening a fastener such as a bolt (hereinafter referred to as a bolt) in the clutch mode. FIG. 7 is a diagram illustrating the control based on the positional relationship between the hammer 42 and the anvil 52 in the clutch mode. FIG. 8 is a diagram illustrating a difference in control during normal rotation and reverse rotation of the hammer 42. FIG. FIG. 7 illustrates an example of a type in which the relative rotation angle between the hammer 42 and the anvil 52 is 180 degrees.

  The clutch mode is a mode in which the driving of the motor 3 is stopped when the current flowing through the motor 3 increases to a target value (target torque) while the hammer 42 and the anvil 52 are integrally rotated. When the trigger 25 is pulled while the anvil 52 and the anvil 52 are separated from each other, a hit is applied to the anvil 52, and a torque exceeding the target value may be supplied to the fastener only by the hit. In particular, such a problem becomes conspicuous when retightening a screw that has been fastened once again.

  Therefore, in the clutch mode at the time of bolt fastening, pre-start control is performed to bring the hammer 42 into contact with the anvil 52 without rotating the anvil 52. Specifically, a pre-starting forward voltage (for example, 1.5 V) is applied to the motor 3. The pre-start of the present embodiment is control for bringing the hammer 42 into contact with the anvil 52 in advance before fastening. Specifically, when the hammer 42 comes into contact with the anvil 52, the anvil 52 is not rotated. A voltage in the range is applied to the motor 3 to bring the hammer 42 into contact with the anvil 52.

  Here, in the conventional pre-start, the pre-start was performed for a certain period regardless of the distance between the hammer 42 and the anvil 52, and therefore it took extra time to shift to the actual fastening operation. Therefore, in the present embodiment, the pre-start period is changed according to the distance between the hammer 42 and the anvil 52. Specifically, when the rotation speed of the motor 3 becomes smaller than a threshold value n (for example, 200 rpm), it is determined that the hammer 42 and the anvil 52 are in contact (detect a load), and the pre-start is finished. Transition to control, eg, soft start. Accordingly, in the case of the distance between the hammer 42 and the anvil 52 as shown in FIGS. 7 (2) and (3), the distance between the hammer 42 and the anvil 52 is larger than that shown in FIG. 7 (1). It is possible to finish the pre-start in a short time and shift to the next control. In the present embodiment, an increase in the load on the motor 3 (contact between the hammer 42 and the anvil 52) is detected by a decrease in the rotational speed. However, an increase in the load on the motor 3 may be detected by an increase in the current value. .

  When the pre-start is completed, the process proceeds to a soft start. When the soft start is completed, the process proceeds to a normal control, and the motor is activated when the current flowing through the motor 3 increases to a target value (target torque set by the torque setting dial). The power supply to 3 is stopped. Soft start is control in which the PWM duty is gradually increased to a target value at a constant increase rate in order to prevent an excessive start current from being generated when the motor 3 is started. In this embodiment, after the pre-start, the control is shifted to the normal control via the soft start. However, the control may be shifted to the normal control after the pre-start.

  Next, control when the bolt is loosened in the clutch mode (when the hammer 42 is reversely rotated) will be described with reference to FIG. In addition, the shape of the hammer 42 and the anvil 52 in FIG. 8 will be described by exemplifying a type in which the hammer 42 and the anvil 52 are in contact with each other only in one circumferential direction.

  As described above, at the time of fastening the bolt (the hammer 42 rotates in the clockwise direction), the hammer 42 and the anvil 52 are brought into contact with each other in the pre-start, and then the soft start is started (FIG. 8 (1)). On the other hand, in this embodiment, when the bolt is loosened (the hammer 42 rotates counterclockwise), the pre-start is not performed (FIG. 8 (2)). The bolts that are fastened may not be loosened due to rust or the like, even if the same force is applied as when fastened. In addition, the dynamic friction coefficient between the screw and the work material when tightening the screw and the static friction coefficient between the screw and the work material when loosening the screw satisfy the dynamic friction coefficient <static friction coefficient. May not be possible. However, in the present embodiment, the hammer 42 is accelerated during the soft start control to collide with the anvil 52, so that the torque setting value of the electronic pulse driver 1 is the same when the bolt is tightened and when the bolt is loosened. However, the bolt can be loosened. In FIG. 8, the process starts from the soft start, but can also start from the normal control.

  Next, the case where the operation mode is set to the pulse mode will be described with reference to FIG.

  FIG. 9 is a diagram for explaining control when fastening a bolt in the pulse mode. When the operation mode is set to the pulse mode, when the trigger 25 is operated, the control unit 7 first rotates the motor 3 continuously at the rotation speed A (for example, 17000 rpm), and the torque of the motor 3 is increased. When the predetermined value is reached, the mode shifts to the pulse mode, and the motor 3 is rotated forward and reverse alternately. Since the pulse mode is a mode in which a fastening force is applied by striking, the bit is likely to come off the bolt (come out) when shifting from the continuous rotation to the pulse mode. Therefore, in the present embodiment, in the pulse mode, the motor 3 is rotated forward at a rotational speed B (for example, 10000 rpm) lower than the rotational speed A. As a result, the torque applied to the bit is reduced, so that it is possible to prevent a come-out when the mode is shifted to the pulse mode. In the pulse mode of the present embodiment, forward rotation and reverse rotation are alternately performed. However, it is only necessary to perform forward rotation intermittently. For example, forward rotation and stop may be alternately performed.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 10 is a diagram for explaining the control when the drill screw 53 is fastened to the iron plate S in the pulse mode, and FIG. 11 is a diagram showing the state of the drill screw 53 when the drill screw 53 is fastened to the iron plate S in the pulse mode. is there. The drill screw is a screw provided with a drill blade that opens a hole in the iron plate at the tip of the screw, and includes a screw head 53A, a seating surface 53B, a screw portion 53C, a screw tip 53D, and a drill 53E. (FIG. 11).

  In the pulse mode according to the present embodiment, PWM control is performed to change the rotation speed. First, when the trigger 25 is operated (t1 in FIG. 10), the control unit 7 drives the motor 3 at the rotational speed a. In the pulse mode, since it is not important to fasten with accurate torque, the step corresponding to the pre-start in the clutch mode is omitted. For the sake of simplicity, the illustration of soft start is omitted in FIG.

  In a state where the iron plate S and the drill 53E of the drill screw 53 are in contact with each other as shown in FIG. 11A, it is necessary to make a pilot hole in the iron plate S with the drill 53E, so the motor 3 is rotated as shown in FIG. It is rotated at a high speed by a number a (for example, 17000 rpm). When the tip of the drill screw 53 bites into the iron plate and the screw tip 53D reaches the iron plate S, the friction between the screw portion 53C and the iron plate S becomes resistance and the current value increases ((b) in FIGS. 10 and 11). When the current value exceeds a threshold value C (for example, 11 A), the mode shifts to the first pulse mode and repeats normal rotation and reverse rotation (t2 in FIG. 10). Here, in the present embodiment, in the first pulse mode, the motor 3 is rotated forward at a rotational speed b (for example, 6000 rpm) lower than the rotational speed a. When the seat surface 53B is seated on the iron plate S, the current value increases rapidly. Here, in the present embodiment, when the current increase rate exceeds a predetermined value, the mode shifts to the second pulse mode (t3 in FIG. 10). In the second pulse mode, the motor 3 is rotated forward at a rotational speed c (for example, 3000 rpm) lower than the rotational speed b. Thereby, it is possible to prevent the drill screw 53 from being damaged and the head of the drill screw 53 from being licked due to excessive torque applied to the drill screw 53 by the bit.

  The electronic pulse driver of the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims.

  For example, the control when the bolt is loosened (reverse rotation) in the clutch mode in the first embodiment can be realized by other methods. FIG. 12 is a diagram illustrating clutch mode control according to a modification. FIG. 12 (1) shows the control when the motor 3 is rotated forward, and FIG. 12 (2) shows the control when the motor 3 is reversed.

  As shown in FIG. 12 (2), the electronic pulse driver 1 of the modified example supplies electric power having a larger PWM duty to the motor 3 during reverse rotation than during normal rotation. Thereby, the hammer 42 collides with the anvil 52 more strongly at the time of reverse rotation than at the time of normal rotation, so that it is easy to loosen the bolt. However, the PWM duty at the time of reverse rotation is set in a range where no overcurrent occurs.

  Also, instead of increasing the PWM duty, a capacitor is provided, and the electric power stored in the capacitor is also supplied at the time of reverse rotation, so that a large electric power may be supplied to the motor 3, or the rotational speed of the motor 3 is simply increased. Also good. Further, the angle of rotation until the hammer 42 contacts the anvil 52 during reverse rotation may be controlled to be larger than the angle of rotation until the hammer 42 contacts the anvil 52 during forward rotation. Specifically, for example, at the time of reverse rotation, the angle (acceleration distance) between the hammer 42 and the anvil 52 can be increased by rotating the motor 3 forward for a minute time and then reverse rotation. Can be made to collide strongly.

1. Electronic pulse driver 3. Motor 3A. Rotor 4. Hammer section 5. Anvil section 42 Hammer 52 Anvil 7. Control section

Claims (6)

A motor for supplying driving force;
A hammer rotated in the forward or reverse direction by the driving force;
An anvil hit by the hammer rotated in the forward direction or the reverse direction;
An electric tool comprising
The rotation speed of the hammer immediately before the hammer rotated in the reverse rotation direction contacts the anvil is greater than the rotation speed of the hammer immediately before the hammer rotated in the forward rotation direction contacts the anvil. An electric tool characterized by that. A power supply unit for supplying driving power to the motor;
The power supply unit supplies more driving power to the motor when rotating the hammer in the reverse direction than when rotating the hammer in the forward direction at the start of supply. The electric tool according to 1. A power supply unit for supplying driving power to the motor;
The power supply unit has a larger driving power for the motor until the hammer rotated in the reverse direction contacts with the anvil than when the hammer rotated in the forward direction contacts with the anvil. The power tool according to claim 1, wherein the power tool is supplied.   The power supply unit has a PWM duty ratio for the motor until the hammer rotated in the reverse rotation direction contacts the anvil rather than until the hammer rotated in the normal rotation direction contacts the anvil. The power tool according to claim 3, wherein driving power having a large sum is supplied.   The angle at which the hammer rotated in the reverse rotation direction contacts with the anvil is larger than the angle at which the hammer rotated in the normal rotation direction contacts with the anvil. The electric tool according to claim 1.   When the hammer is rotated in the forward rotation direction, a pre-start is performed to bring the hammer into contact with the anvil with a force that does not rotate the anvil, and when the hammer is rotated in the reverse rotation direction, the pre-start is performed. The power tool according to claim 1, wherein there is no power tool.

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