JP2013233637A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool capable of ensuring stability of a user's operation even when an auxiliary handle is not used.SOLUTION: A pressure sensor installed in the recess of a handle mounting part of a power tool body 11 detects the presence or absence of a gripping force by a user of an auxiliary handle 12 having a protrusion to fit in the recess. When the power tool 10 is at work, a relative torque value generated between the power tool body 11 and the auxiliary handle 12 is different between the presence and absence of the gripping force. It is possible, therefore, to detect whether or not there is a gripping force by the user of the auxiliary handle 12 by detection of the relative torque value by the pressure sensor. When it is detected that the auxiliary handle 12 is not gripped by the user, the control unit stops a supply of driving current to motor, so that the output torque as the power tool 10 can be limited.

Description

  The present invention relates to a power tool using an auxiliary handle.

  Conventionally, as shown in Patent Document 1, for example, an electric tool is provided with an auxiliary handle for the electric tool main body, and a user can hold the holding portion of the electric power tool main body and the auxiliary handle firmly with both hands. Some have done.

JP 2002-205285 A

  However, in the power tool as described above, the maximum value of the output torque is set on the assumption that the grip portion of the power tool body and the auxiliary handle are gripped with both hands. Therefore, if the user grips the power tool with one hand without using the auxiliary handle and the output torque of the power tool increases more rapidly than expected, the reaction from the power tool As a result, the user's hand is shaken, and the work may not be performed stably.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric tool that can stabilize the work of a user even when an auxiliary handle is not used. .

  In order to solve the above problems, an electric tool of the present invention includes an electric motor including a motor, a power transmission unit that converts rotational power of the motor into a desired output and transmits the output to an output shaft, and a control unit that performs output control. An electric tool having an auxiliary handle for holding the electric power tool main body with respect to the tool main body, further comprising a grip detection unit that detects gripping by a user of the auxiliary handle, and the control unit detects the grip detection If the user detects that the user does not hold the auxiliary handle, the output torque is limited.

  Further, in the above configuration, the grip detection unit is configured to be able to detect a physical quantity generated between the power tool main body and the auxiliary handle in accordance with the operation of the power tool, and the control unit is configured to detect the detected electric motor. It is preferable to determine the presence or absence of gripping by the user of the auxiliary handle based on a physical quantity generated between the tool body and the auxiliary handle.

Moreover, the said structure WHEREIN: It is preferable that the said holding | grip detection part is provided in the said electric tool main body side.
In the above configuration, the grip detection unit is preferably provided on the auxiliary handle side.

  Further, in the above configuration, the control unit sets the upper limit value of the output torque to an upper limit value that differs depending on whether or not the auxiliary handle is gripped, and the auxiliary handle is not gripped more than when the grip of the auxiliary handle is detected. If this is detected, it is preferable to set the upper limit value lower.

  In the above configuration, the control unit detects a change amount of the target value related to the limitation of the output torque, and limits the output torque when the detected change amount of the target value is larger than a threshold value. preferable.

  Further, in the above configuration, the power transmission unit can be shifted to a plurality of reduction ratios, and the control unit limits the output torque based on whether or not the auxiliary handle is gripped only when driving at a predetermined high torque, and otherwise During the low torque driving, it is preferable not to limit the output torque.

  Further, in the above configuration, the power transmission unit can be shifted to a plurality of reduction ratios, and can be automatically shifted by the control unit, and the control unit can be operated by the user at the grip detection unit. When it is detected that the auxiliary handle is not gripped, it is preferable to limit the output torque by prohibiting a change to a reduction ratio at which a predetermined high torque can be output.

  In the above configuration, it is preferable that the control unit restricts the output torque only when the auxiliary handle is gripped only during a predetermined high torque drive, and does not restrict the output torque during other low torque drive. .

  Further, in the above configuration, the auxiliary handle is detachable with respect to the electric tool body, and includes an attachment / detachment detection unit that detects whether the auxiliary handle is attached to the electric tool body, and the control unit includes the attachment / detachment unit. When the detection unit detects that the auxiliary handle is attached to the power tool main body, it is preferable to limit the output torque on the condition that the auxiliary handle is gripped by a user.

  ADVANTAGE OF THE INVENTION According to this invention, even when not using an auxiliary | assistant handle, the electric tool which can aim at the stability of a user's operation | work can be provided.

The perspective view which shows the electric tool in embodiment. The side view which shows the electric tool which a part of side was notched in order to show a power transmission part. The side view which shows the electric tool which a part of side was notched in order to show a power transmission part. The side view which shows the single body of an auxiliary | assistant handle. Sectional drawing which shows the attachment state to the electric tool main body of an auxiliary | assistant handle. The block diagram for demonstrating the electrical connection of an electric tool. The flowchart for demonstrating the process of a control part. Sectional drawing which shows the structure of the auxiliary | assistant handle in another example. The side view which shows the structure of the auxiliary | assistant handle in another example. Sectional drawing which shows a part of electric tool in another example.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the power tool 10 of the present embodiment is a tool used as a drill driver, for example, and includes a power tool body 11 and an auxiliary handle 12 that can be attached to and detached from the power tool body 11. ing. The electric tool main body 11 has a substantially T-shaped main body case 23 composed of a substantially cylindrical body portion 21 and a grip portion 22 that extends downward from the middle of the body portion 21 in the longitudinal direction. Yes. Further, the electric tool main body 11 has a battery pack 24 that can be attached to and detached from the main body case 23. In the present embodiment, the longitudinal direction of the body portion 21 is defined as the front-rear direction, the direction perpendicular to the front-rear direction in the substantially extending direction of the grip portion 22 is defined as the up-down direction, and the direction orthogonal to the front-rear direction and the up-down direction To do.

  As shown in FIG. 2, a motor 25 is housed in a longitudinal rearward position of the body portion 23 of the main body case 23, and includes a speed reduction mechanism 26 and a clutch mechanism (not shown) at a forward position thereof. The transmission part 27 is accommodated. A chuck 28 provided at the front end of the electric power tool body 11 is configured such that a driver tip tool (not shown) is detachable, and an output shaft 38 (see FIG. 2) in the chuck 28 to which the output of the power transmission unit 27 is transmitted. And the tool can be driven and connected.

  The speed reduction mechanism 26 of the power transmission unit 27 is a three-stage planetary gear mechanism. The gear mechanism of each stage is meshed with the sun gear, the planetary gear arranged around the sun gear, and meshed with the planetary gear. With ring gear. A sun gear 31 of a first-stage gear mechanism is provided on the rotating shaft 29 of the motor 25 so as to be integrally rotatable. The ring gear 32 of the second stage gear mechanism is held in the case 23 so as to be movable within a predetermined range in the axial direction. A shift changeover switch 33 is provided on the upper surface of the case 23 so that the user can change the reduction ratio of the reduction mechanism 26. The shift switch 33 is, for example, a slide switch, and is a switch that switches between high speed low torque drive (H gear) and low speed high torque drive (L gear) by sliding the position in the front-rear direction. The gear change switch 33 is drivably coupled to a groove formed on the outer peripheral surface of the second stage ring gear 32 via a coupling member 34.

  When the ring gear 32 is moved forward (on the output shaft 38 side) by the sliding operation of the speed change switch 33, the ring gear 32 is engaged with the engaging portion 35 provided in the case 23 and cannot rotate. That is, the second-stage reduction mechanism functions, and the rotational power of the motor 25 is reduced by the first to third gear mechanisms and transmitted to the output shaft 38 side. The state shown in FIG. 2 shows a state of low speed high torque drive (L gear) in which the second stage gear mechanism functions.

  On the other hand, when the ring gear 32 moves rearward (on the motor 25 side), the ring gear 32 is disengaged from the engaging portion 35 and becomes rotatable, and is meshed with the first-stage transmission gear 36. That is, the second stage gear mechanism, including the second stage ring gear 32, rotates as a whole and does not function as a speed reduction mechanism, and the rotational power of the motor 25 is the first and third stage gear mechanisms. Only when it is decelerated, it is transmitted to the output shaft 38 side. The state shown in FIG. 3 shows a state of high speed low torque drive (H gear) in which the second stage gear mechanism does not function.

  The shift switch 33 is provided with an operation position detection switch 37 that outputs an on / off signal corresponding to the operation position. The operation position detection switch 37 outputs, for example, an ON signal when operated to the L gear for low speed and high torque driving, and an OFF signal when operated to the H gear for high speed and low torque driving.

  The third stage gear mechanism of the speed reduction mechanism 26 is drivingly connected to the output shaft 38. The output shaft 38 is rotatably supported by a bearing (not shown) provided in the case 23 and is configured to transmit a driving force to a tip tool attached to the chuck 28. A clutch mechanism is provided between the speed reduction mechanism 26 (third gear mechanism) and the output shaft 38, and the speed reduction mechanism 26 and the output are output according to the load torque input via the output shaft 38. The shaft 38 is mechanically switched between connected and disconnected.

  As shown in FIGS. 1 and 2, a rotation direction changeover switch 39 for switching the rotation direction of the motor 25 is provided in the vicinity of the connection portion of the body portion 21 of the main body case 23 to the grip portion 22. The rotation direction changeover switch 39 is configured to be switchable to, for example, three states in which the motor 25 is rotated forward, reversely, and stopped. For example, the trigger switch 41 protrudes forward from the grip portion 22 in a state of being biased by a spring, for example. A battery pack mounting portion 22a protruding forward is formed at the lower end of the grip portion 22, and a battery pack 24 is mounted on the battery pack mounting portion 22a. Further, a control unit 61 (see FIG. 6) that includes the motor 25 and performs overall control of the electric tool 10 is accommodated in the battery pack mounting unit 22a.

Next, the auxiliary handle 12 will be described.
As shown in FIG. 1, the auxiliary handle 12 includes a mounting portion 51 that is attached to the body portion 21 of the electric power tool main body 11 and a handle portion 52 that is held by the user. The auxiliary handle 12 is mounted such that its attachment portion 51 is attached to the barrel portion 21 at a position slightly ahead of the barrel portion 21 of the electric power tool body 11, and the handle portion 52 protrudes to the left side, for example. Since the auxiliary handle 12 can be attached to and detached from the body portion 21 by the attachment portion 51 and the attachment position can be changed, the handle portion 52 can be attached so as to protrude to the right side of the electric power tool main body 11.

  As shown in FIG. 2, a handle attachment portion 42 for attaching the attachment portion 51 of the auxiliary handle 12 is provided on the body portion 21 of the electric tool main body 11. The handle attachment portion 42 is formed by recessing the outer peripheral surface of the body portion 21 according to the shape of the attachment portion 51. The handle attachment portion 42 is provided with one concave portion 42a (see FIG. 5) on the left and right sides formed in a substantially rectangular cross section so as to extend along the direction perpendicular to the axis. Each concave portion 42a is provided with a pressure sensor 43 on each inner wall in the vertical direction.

  The attachment portion 51 of the auxiliary handle 12 includes a tightening portion 54 formed in a substantially cylindrical shape, and an annular portion 55 extending from the side surface of the tightening portion 54. The annular portion 55 has a substantially annular shape formed in a direction orthogonal to the axial direction of the tightening portion 54. The attachment portion 51 is provided with a slit 56 across the fastening portion 54 and the annular portion 55, and the interval between the slits 56 can be changed in the axial direction of the fastening portion 54, that is, the diameter (inner diameter) of the annular portion 55 can be changed. It is like that. Further, on the inner peripheral surface of the annular part 55, a pair of convex parts 53 fitted into the concave part 42 a of the handle attachment part 42 are formed toward the radially inner side of the annular part 55 (see FIG. 4 and FIG. 4). (See FIG. 5).

  The handle portion 52 is formed so as to extend along the axial direction of the tightening portion 54 and has an elongated and substantially cylindrical shape that can be easily gripped by the user's hand. A flange portion 52 a is formed on the base end side (attachment portion 51 side) of the handle portion 52.

  Further, the auxiliary handle 12 is provided with a bolt 57 inserted in the axial direction into the tightening portion 54 and the handle portion 52, and both side portions separated by the slit 56 are connected by the bolt 57. For example, when the handle portion 52 is rotated, the distance between the slits 56 can be changed by the action of a bolt 57 that rotates with the handle portion 52. That is, when attaching the auxiliary handle 12, the interval between the slits 56, that is, the annular portion 55, so that the annular portion 55 of the attachment portion 51 can be inserted from the distal end side of the body portion 21 of the power tool body 11 to the handle attachment portion 42. The diameter of is once increased. Then, the auxiliary handle 12 is fixed to the power tool body 11 by performing tightening to reduce the interval between the slits 56 at the place where the annular portion 55 of the attachment portion 51 is disposed on the handle attachment portion 42.

  Further, at the time of fixing, as shown in FIG. 5, each convex portion 53 provided inside the annular portion 55 of the auxiliary handle 12 is fitted into each concave portion 42 a of the handle mounting portion 42. When the user grips the auxiliary handle 12 and performs the operation with the electric tool 10, a rotational force around the axial direction of the electric tool body 11 is generated, and therefore, the relative force between the auxiliary handle 12 (convex portion 53) is generated. Force in the rotational direction is generated, and the force (relative torque) is detected by the pressure sensor 43. That is, when the user is holding the auxiliary handle 12, the relative torque is larger than when the user is not holding it, so the user can hold the auxiliary handle 12 with the magnitude of the relative torque detected by the pressure sensor 43. It can be detected whether or not.

Next, electrical connection of the power tool 10 will be described.
As shown in FIG. 6, power is supplied from the battery pack 24 (not shown in FIG. 6) to the control unit 61 that performs output control of the electric power tool main body 11, and the speed change switch 33 (operation position detection switch 37). Signals from various switches such as the rotation direction switch 39 and the trigger switch 41 are input. With respect to the operation position detection switch 37, the control unit 61 grasps based on a signal from the operation position detection switch 37 whether the gear change switch 33 is switched to the H gear or the L gear. For the rotation direction changeover switch 39, the control unit 61 switches and stops the rotation direction of the motor 25 based on selection of normal rotation, reverse rotation, and stop of the motor 25 by the rotation direction changeover switch 39. With respect to the trigger switch 41, the trigger switch 41 outputs a signal corresponding to the pull-in amount, and the control unit 61 performs output control according to the pull-in amount.

  The control unit 61 receives a detection signal corresponding to the drive current supplied from the current detection unit 62 to the motor 25. The controller 61 detects the load torque applied to the output shaft 38 based on the detection signal from the current detector 62. The controller 61 controls the output of the motor 25 based on the pull-in amount of the trigger switch 41 and the detected load torque.

  Further, in the mounted state of the auxiliary handle 12, the control unit 61 receives from the pressure sensor 43 provided on the handle mounting portion 42 (see FIGS. 2 and 5) of the electric tool main body 11 between the tool main body 11 and the auxiliary handle 12. A detection signal corresponding to the magnitude of the relative torque generated therebetween is input. That is, the control unit 61 detects whether or not the auxiliary handle 12 is gripped during the operation of the power tool 10 based on the input detection signal. When it is detected that the user is holding the auxiliary handle 12, the control unit 61 controls the motor 25 as usual. On the other hand, when it is detected that the user is not gripping the auxiliary handle 12, the control unit 61 supplies the output torque of the motor 25, for example, as a current supply only when low-speed high-torque driving (L gear) is performed. It is suppressed by stopping and the output torque as the electric tool 10 is limited. During high-speed and low-torque driving (H gear), the control unit 61 does not limit the output torque because the torque originally does not increase beyond a predetermined value.

Next, the operation (action) of the electric power tool 10 will be described with reference to the output control process of the control unit 61 shown in FIG.
When the trigger switch 41 is pulled in by the user (step S1), the control unit 61 monitors the speed change mode based on a signal from the operation position detection switch 37 of the speed change switch 33 (step S2). Next, the control unit 61 determines whether or not the speed change mode is set to the L gear for low speed and high torque drive (step S3). When the high gear is set to the high speed and low torque drive, the control unit 61 repeats the process from step S2.

  When the L gear is set, the control unit 61 detects a relative torque generated between the electric power tool main body 11 and the auxiliary handle 12 as a pressure value based on a signal from the pressure sensor 43, and the pressure It is determined whether the value is greater than or equal to a threshold value P (step S4). This threshold value P is a grip detection threshold value for determining whether the user is gripping the auxiliary handle 12, and the relative torque generated between the electric power tool body 11 and the auxiliary handle 12 during use is determined by the user of the auxiliary handle 12. It is set to a value that can be distinguished by the presence or absence of gripping.

  Based on the determination result in step S4, the control unit 61 sets the threshold value of the drive current supplied to the motor 25 to one of the threshold value A and the threshold value B (steps S5 and S6). The target of the threshold value may be, for example, the output torque of the electric tool 10 other than the drive current supplied to the motor 25, or both.

  When the relative torque generated between the electric power tool body 11 and the auxiliary handle 12 is equal to or greater than the threshold value P, it is determined that the user is holding the auxiliary handle 12. That is, in supporting the electric power tool 10, it is determined that the user is firmly supporting the grip portion 22 and the auxiliary handle 12 of the tool body 11 with both hands, and the threshold value A that enables high torque work is set. (Step S5).

  On the other hand, when the relative torque generated between the electric power tool body 11 and the auxiliary handle 12 is smaller than the threshold value P, it is determined that the user is not holding the auxiliary handle 12. That is, in supporting the electric power tool 10, it is determined that the user is supporting with only one hand of the grip portion 22 of the tool body 11, and the threshold B smaller than the threshold A is set, that is, the output torque is suppressed. A threshold value B is set (step S6).

  Next, the control unit 61 monitors the target value, in this embodiment, the current value of the drive current to the motor 25 based on the signal from the current detection unit 62 (step S7), and the current value of the monitored motor 25 is determined. It is determined whether or not the thresholds A and B are exceeded (step S8). That is, it is determined whether the output torque of the motor 25 is within a range where the work can be appropriately performed, either by a two-hand operation using the auxiliary handle 12 or a one-hand operation without using the auxiliary handle 12.

  When the drive current to the motor 25 exceeds the thresholds A and B, that is, the output torque corresponding to the two-hand operation or the one-hand operation, the control unit 61 stops supplying the drive current to the motor 25 (step S9). That is, in both the two-handed work and the one-handed work, the output torque of the motor 25 is suppressed in consideration of work stability and the like, and the output torque as the electric tool 10 is limited.

  Thus, during low-speed high-torque driving (L gear), the output torque is greatly limited particularly when the user is not gripping the auxiliary handle 12, so that the user's hand is moved by the reaction from the power tool 10. The possibility of being shaken can be reduced, and the stability of work using the electric power tool 10 is improved.

  In step S8, when the current value of the drive current supplied to the motor 25 is smaller than the threshold values A and B, the control unit 61 monitors the change amount of the target value, and in this embodiment, monitors the current change amount of the motor 25 ( Step S10). What is monitored is not only the current change amount of the motor 25 but also, for example, the rotation speed change amount of the motor 25, the output torque change amount of the electric tool 10, etc., or a combination thereof including the current change amount is also possible. . The controller 61 determines the current change amount of the monitored motor 25 (step S11). That is, although the drive current (output torque) of the motor 25 is less than the threshold values A and B, it is determined whether or not the fluctuation of the output torque (load torque) is large. If the current change amount of the motor 25 is less than the threshold value ΔC, the control unit 61 returns the process to step S2.

  When the current change amount of the motor 25 becomes equal to or greater than the threshold value ΔC, the control unit 61 stops supplying the drive current to the motor 25 (step S9). That is, in a situation where the output torque (load torque) of the motor 25 increases rapidly, the reaction from the electric tool 10 to the hand held by the operator is large, so the output torque of the motor 25 is suppressed, and the electric tool 10 The output torque is limited. Also by this, the reaction which acts on the user's hand from the electric power tool 10 can be reduced, which contributes to the improvement of work stability.

This embodiment has the following effects.
(1) The pressure sensor 43 provided in the concave portion 42a of the handle attachment portion 42 of the electric tool main body 11 detects whether or not the user holds the auxiliary handle 12 having the convex portion 53 fitted thereto. Since the relative torque generated between the power tool main body 11 and the auxiliary handle 12 during operation of the power tool 10 differs depending on whether the gripping is present or not, the gripping of the auxiliary handle 12 is detected by detecting the relative torque by the pressure sensor 43. The presence or absence can be detected. When the control unit 61 detects that the user is not gripping the auxiliary handle 12, the control unit 61 stops the drive current supplied to the motor 25, and the output torque of the electric tool 10 is limited. That is, particularly in the case of the one-hand support of the electric power tool 10, there is a high possibility that it cannot respond to the reaction from the electric power tool 10 due to a sudden increase in output torque (load torque), so the auxiliary handle 12 is gripped by the user during operation. If not, control for limiting the output torque is performed. Thus, when the auxiliary handle 12 is not used, the output torque of the electric tool 10 is limited based on the user's support situation, so that the stability of the user's work can be achieved.

  (2) Since the physical quantity such as the relative torque generated between the power tool main body 11 and the auxiliary handle 12 during operation of the power tool 10 is different between the presence and absence of gripping, the detection of the relative torque using the pressure sensor 43 is performed. Thus, it is possible to easily detect whether the auxiliary handle 12 is gripped.

  (3) Since the pressure sensor 43 that detects whether or not the auxiliary handle 12 is gripped is provided on the power tool body 11 side, electrical connection with the control unit 61 installed in the same tool body 11 is easy. In particular, when the auxiliary handle 12 is configured to be detachable from the electric tool main body 11, the effect is great.

  (4) The controller 61 sets the upper limit value (threshold value) of the output torque to different upper limit values (threshold values A and B) depending on whether or not the auxiliary handle 12 is gripped. That is, it is possible to easily limit the output torque depending on whether or not the auxiliary handle 12 is held.

  (5) The control unit 61 detects the change amount of the target value related to the output torque limit (current change amount of the motor 25), and limits the output torque when the detected change amount is larger than the threshold value ΔC. . Therefore, not only the limitation based on the absolute value of the output torque but also the limitation based on the output torque that increases instantaneously is possible, so that the stability of the work using the electric power tool 10 can be further improved.

  (6) The control unit 61 limits the output torque based on whether or not the auxiliary handle 12 is gripped only when driving the L gear with low speed and high torque, and does not limit the output torque when driving the H gear with high speed and low torque. That is, when the H gear is driven, the torque is not originally increased and can be fully supported by the support of the user. Therefore, the workability can be improved by limiting the output torque as much as possible.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the configuration for detecting whether or not the auxiliary handle 12 is gripped is an example, and may be changed as appropriate. For example, as shown in FIG. 8, a pressure sensor 71 and a spring 72 may be provided in the auxiliary handle 12a to constitute a grip detection unit. Specifically, a pressure sensor 71 and a spring 72 are provided inside a connection portion between the handle portion 52 and the attachment portion 51. When a force (relative torque generated between the power tool body 11) is applied to the auxiliary handle 12, the handle portion 52 is bent with respect to the mounting portion 51, and a force is applied to the pressure sensor 71 at a predetermined portion inside the handle portion 52. In this case, since the acting force varies depending on whether or not the handle portion 52 is gripped, it is possible to detect whether or not the auxiliary handle 12a is gripped. The spring 72 is provided to adjust the force applied to the pressure sensor 71 and to maintain a distance from a portion inside the auxiliary handle 12a.

  Further, for example, as in the auxiliary handle 12b shown in FIG. 9, a pressing switch 73 that is turned on / off by the user holding the handle portion 52 on the outer surface of the handle portion 52 may be provided. Even in such a configuration, the presence / absence of gripping of the auxiliary handle 12b can be detected based on the signal from the push switch 73. Further, for example, a capacitance sensor may be provided on the outer surface of the handle portion 52 to detect the presence or absence of the user's grip.

Thus, by providing the grip detection part of the auxiliary handle 12 on the handle 12 side, it is possible to detect the presence or absence of the grip of the user more directly.
-In the electric tool 10 of the said embodiment, the structure which can detect the presence or absence of mounting | wearing of the auxiliary | assistant handle 12 may be provided. For example, as illustrated in FIG. 10, a push switch 74 that is turned on / off in accordance with the attachment / detachment of the auxiliary handle 12 may be provided in the handle attachment portion 42 of the electric tool main body 11. Then, the control unit 61 detects whether or not the auxiliary handle 12 is used when the auxiliary handle 12 is mounted / not mounted based on the on / off signal of the switch 74. When the auxiliary handle 12 is not mounted, the control unit 61 limits the output torque of the electric tool 10. May be performed. Further, if both the presence / absence of the auxiliary handle 12 and the presence / absence of the above-described gripping are used as conditions, the gripping detection of the auxiliary handle 12 becomes more reliable.

  In the above embodiment, the shift mode of the electric tool 10 is detected by the operation position detection switch 37 provided in the shift switch 33 portion. However, the present invention is not limited to this, for example, the second stage ring of the speed reduction mechanism 26 A magnet is provided on the outer peripheral surface of the gear 32, and a Hall element is provided on the inner wall of the case 23 facing the magnet. The deceleration mode may be changed depending on whether the ring gear 32 is rotated, such as rotating when the H gear is driven and non-rotating when the L gear is driven.

  In the above embodiment, the shift mode of the electric tool 10 is switched by manual operation of the shift switch 33, but an automatic shift may be employed. For example, a speed change actuator that changes the position of the second stage ring gear 32 of the power transmission unit 27 is provided, and the control unit 61 drives the speed change actuator according to the load torque applied to the output shaft 38 to automatically change the reduction ratio. It is good also as composition to do. In this case, for example, when the auxiliary handle 12 is not attached or when the attached auxiliary handle 12 is not grasped, the automatic shift from the H gear to the L gear (high torque) side is prohibited, and the output torque Restrictions may be made.

  It should be noted that in a device having a speed reduction mechanism having a plurality of speed reduction ratios (particularly, the speed reduction stage is 2 or 3), the fluctuation of the output torque of the electric power tool 10 tends to be large during the automatic shift, and the fluctuation is abrupt. Therefore, it is significant to limit the output torque.

  Also, when the change ratio of the reduction ratio is 3 or more, the output torque is limited only by a predetermined high torque drive, for example, in the case of two high torque drives on the larger deceleration amount side, depending on whether or not the auxiliary handle 12 is gripped. In the case of high-speed low-torque driving with the smallest deceleration amount, the output torque may not be limited depending on whether the auxiliary handle 12 is gripped.

  Also, in the case of manual shift by operating the shift selector switch, the mode of changing the reduction ratio may be 3 or more. In this case as well, for example, in the case of high-speed low-torque driving with a small deceleration amount, the auxiliary handle 12 is held. The output torque may not be limited depending on the presence or absence.

  In the process of step S9 of FIG. 7 in the above embodiment, the process of limiting the output torque is performed by stopping the drive current supplied to the motor 25. However, other methods may be used. For example, duty control may be performed on the drive current supplied to the motor 25, and the output torque may be limited by lowering the duty ratio. Further, for example, in the drive transmission path from the rotating shaft 29 of the motor 25 to the output shaft 38 of the electric tool 10, for example, the output shaft 38 and the speed reduction mechanism 26 are provided with a brake mechanism, and the output torque is limited by the operation of the brake mechanism. Also good.

  -An acceleration sensor may be provided with respect to the electric tool 10 of the said embodiment, and the vibration of the electric tool 10 may be detected with the acceleration sensor. In this way, the user's shake due to the reaction from the electric power tool 10 can be directly detected, and the output torque may be limited when the shake is large.

  In the processing of steps S7 and S8 in FIG. 7 in the above embodiment, the current value of the drive current supplied to the motor 25 is monitored, but other values may be monitored. For example, the output current (load torque) of the output shaft 38 of the electric power tool 10 may be calculated using the drive current supplied to the motor 25 and monitored. Further, the rotational speed (rotational speed) of the motor 25 may be monitored. Moreover, these combinations may be sufficient. The processing related to this is changed according to the target value to be monitored.

  In the processing of steps S10 and S11 of FIG. 7 in the above embodiment, the current change amount of the motor 25 is monitored, but other than this may be monitored. For example, the rotational speed change amount of the motor 25, the output torque change amount (load torque change amount) of the electric tool 10, and the like may be monitored. Moreover, these combinations may be sufficient. The processing related to this is changed according to the target value to be monitored.

In the above embodiment, the electric motor 25 is used as the drive source, but a motor that operates with a fluid such as air may be used.
In the above embodiment, the power tool 10 is applied to a drill driver, but may be applied to another power tool having an auxiliary handle. In this case, the output of the electric tool 10 is a rotational output, but it may be, for example, an electric tool that performs a reciprocating linear motion. Also in this case, a relative force is generated between the auxiliary handle and the electric power tool main body, and the force varies depending on whether or not the auxiliary handle is gripped.

  DESCRIPTION OF SYMBOLS 10 ... Electric tool, 11 ... Electric tool main body, 12, 12a, 12b ... Auxiliary handle, 25 ... Motor, 27 ... Power transmission part, 38 ... Output shaft, 43 ... Pressure sensor (grip detection part), 61 ... Control part ( Grip detection unit, attachment / detachment detection unit) 71, 73 ... pressure sensor (grip detection unit), 74 ... push switch (attachment / detachment detection unit), A, B ... threshold (upper limit), ΔC ... threshold.

Claims (10)

Auxiliary for holding the electric tool main body with respect to the electric power tool main body comprising a motor, a power transmission unit that converts the rotational power of the motor into a desired output and transmits the output to an output shaft, and a control unit that performs output control A power tool with a handle,
A grip detection unit for detecting gripping by a user of the auxiliary handle;
When the grip detection unit detects that the user is not gripping the auxiliary handle, the control unit limits the output torque. The power tool according to claim 1,
The grip detection unit is configured to be able to detect a physical quantity generated between the power tool body and the auxiliary handle in accordance with the operation of the power tool.
The said control part determines the presence or absence of the holding | grip by the user of the said auxiliary handle based on the physical quantity which arises between the detected said electric tool main body and the said auxiliary handle. In the electric tool according to claim 1 or 2,
The power tool, wherein the grip detection unit is provided on the power tool main body side. In the electric tool according to claim 1 or 2,
The power tool, wherein the grip detection unit is provided on the auxiliary handle side. In the electric tool according to any one of claims 1 to 4,
The control unit sets the upper limit value of the output torque to a different upper limit value depending on whether or not the auxiliary handle is gripped, and detects that the auxiliary handle is not gripped more than when the grip of the auxiliary handle is detected The power tool is characterized in that the upper limit value is set lower. In the electric tool according to any one of claims 1 to 5,
The control unit detects a change amount of a target value related to the limitation of the output torque, and limits the output torque when the detected change amount of the target value is larger than a threshold value. . In the electric tool according to any one of claims 1 to 6,
The power transmission unit is capable of shifting to a plurality of reduction ratios,
The electric power tool is characterized in that the control unit limits the output torque based on whether or not the auxiliary handle is gripped only during a predetermined high torque drive, and does not limit the output torque during other low torque drives. In the electric tool according to any one of claims 1 to 6,
The power transmission unit is capable of shifting to a plurality of reduction ratios, and is automatically shifted by the control unit,
When the grip detection unit detects that the user is not gripping the auxiliary handle, the control unit prohibits changing to a reduction ratio at which a predetermined high torque can be output, and the output torque The electric tool characterized by performing the restriction | limiting of this. The power tool according to claim 8,
The electric power tool is characterized in that the control unit limits the output torque based on whether or not the auxiliary handle is gripped only during a predetermined high torque drive, and does not limit the output torque during other low torque drives. In the electric tool according to any one of claims 1 to 9,
The auxiliary handle is detachable from the electric tool main body, and includes an attachment / detachment detection unit that detects whether the auxiliary handle is attached to the electric tool main body,
When the attachment / detachment detection unit detects that the auxiliary handle is attached to the power tool body, the control unit limits the output torque on the condition that the auxiliary handle is gripped by a user. A power tool characterized by performing.