JP2013233636A - 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: An auxiliary handle 12 includes a pressure sensor 58, and the gripping force by a user of the auxiliary handle 12 is detected by a control unit. The control unit prohibits a change of a reduction ratio to a low speed high torque drive (L gear) side in a speed reduction mechanism of a transmission part when the control unit detects that the user is not gripping the auxiliary handle 12, thereby limiting the output torque of a power tool 10.

Description

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

  2. Description of the Related Art Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-133620, an automatic power transmission is a gear shifter that automatically controls a power transmission unit that decelerates and transmits the rotational power of a motor, and automatically changes a reduction ratio according to a load torque. There is something to do. Particularly in such a power tool, a large reaction is transmitted to the user's hand holding the power tool when automatic shifting is performed from high speed and low torque to low speed and high torque. Therefore, in such an electric tool, for example, as shown in Patent Document 2, an auxiliary handle is provided for the electric tool body, and the user can firmly hold the grip portion of the electric tool body and the auxiliary handle with both hands. Some are configured to be gripped.

JP 2010-046750 A JP 2009-233773 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-described problem, an electric tool of the present invention includes a motor, a power transmission unit configured to decelerate and transmit the rotational power of the motor to the output shaft, and to change a reduction ratio thereof, and the output For a power tool body including a torque detection unit that detects a load torque applied to the shaft, and a control unit that performs control to change a reduction ratio of the power transmission unit according to the detected load torque together with the control of the motor, An electric tool including an auxiliary handle for holding the electric tool main body, the electric tool including a grip detection unit that detects gripping by a user of the auxiliary handle, and the control unit is configured to use the use in the grip detection unit. When it is detected that the person is not gripping the auxiliary handle, the output torque is limited by prohibiting the change of the reduction ratio to the predetermined high torque side in the power transmission unit.

  Further, in the above configuration, the power transmission unit includes a plurality of deceleration stages, and the control unit detects that the user does not grip the auxiliary handle at the grip detection unit. It is preferable that the change to the speed reduction stage capable of outputting a predetermined high torque is prohibited.

  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 block diagram which shows a power transmission part. The perspective view which shows the electric tool of the state which removed the auxiliary handle. The block diagram for demonstrating the electrical connection of an electric tool. The characteristic view which shows the relationship between the rotation speed of the output shaft of an electric tool, and a torque. The perspective view which shows the electric tool of the state which removed the auxiliary handle in another example. The perspective view which shows the electric tool of the state which removed the auxiliary handle 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, the body portion 21 of the main body case 23 accommodates an electric motor 25 at a position on the rear side in the longitudinal direction, and a power transmission portion 27 that decelerates the rotational power of the motor 25 on the front side. Has been. The chuck 26 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 33 in the chuck 26 to which the output of the power transmission unit 27 is transmitted (FIG. 2). And the tool can be driven and connected.

  The power transmission unit 27 includes a speed reduction mechanism 41 and a clutch mechanism 28. The speed reduction mechanism 41 is configured by a planetary gear mechanism having three speed reduction mechanisms 41a, 41b, 41c (in order from the motor 25 side). A first sun gear 42a of the first speed reduction mechanism 41a at the first stage is provided on the rotary shaft 25a of the motor 25 so as to be integrally rotatable. The first speed reduction mechanism 41a includes a plurality of first planetary gears 43a arranged around the first sun gear 42a and meshed therewith, a first ring gear 44a meshed with the first planetary gear 43a, and a first planetary gear. And a first transmission gear 45a that rotatably supports 43a. The first ring gear 44a is fixed to the case 23, and is unable to rotate around the axis of the rotary shaft 25a and is restricted from moving in the axial direction. The first planetary gear 43a circulates around the first sun gear 42a while rotating itself with the rotation of the rotary shaft 25a.

  On the front surface of the first transmission gear 45a, a second sun gear 42b of the second-stage second reduction mechanism 41b is integrally provided. The second speed reduction mechanism 41b includes a plurality of second planetary gears 43b arranged around the second sun gear 42b and meshed therewith, a second ring gear 44b meshed with the second planetary gear 43b, and a second planetary gear. And a second transmission gear 45b that rotatably supports 43b.

  A third sun gear 42c of the third reduction mechanism 41c at the third stage is integrally provided on the front surface of the second transmission gear 45b. A plurality of third planetary gears 43c are meshed with the third sun gear 42c and a third ring gear 44c provided in the case 23 so as to be freely rotatable. The third planetary gear 43c is rotatably supported by a third transmission gear 45c disposed coaxially with the rotation shaft 25a. The third transmission gear 45 c is drivingly connected to the output shaft 33 via the clutch mechanism 28. The output shaft 33 is rotatably supported by a bearing 34 or the like provided in the case 23, and transmits a driving force to a tip tool attached by the chuck 26.

  The second ring gear 44b described above is held with respect to the case 23 so as to be movable within a predetermined range in the axial direction. The second ring gear 44 b is drivingly connected to the output portion 31 of the speed change actuator 29 provided in the case 23. The speed change actuator 29 is, for example, a motor actuator, and changes the position of the second ring gear 44 b by the operation of the output unit 31.

  When the second ring gear 44b is moved forward (on the output shaft 33 side) by the speed change actuator 29, the second ring gear 44b is engaged with the engaging portion 32 provided in the case 23 and cannot rotate. That is, the second reduction mechanism 41b functions, and the rotational power of the motor 25 is reduced by the first to third reduction mechanisms 41a to 41c and transmitted to the output shaft 33 side.

  On the other hand, when the second ring gear 44b moves rearward (motor 25 side), the second ring gear 44b is disengaged from the engaging portion 32 and can rotate, and the first transmission gear 45a Meshed. That is, the second speed reduction mechanism 41b including the second ring gear 44b as a whole rotates integrally and does not function as a speed reduction mechanism, and the rotational power of the motor 25 is reduced only by the first and third speed reduction mechanisms 41a and 41c. And transmitted to the output shaft 33 side. In this way, by changing the position of the second ring gear 44b, the speed reduction stage of the speed reduction mechanism 41 becomes the low speed high torque drive (L gear) side where the second speed reduction mechanism 41b functions and the second speed reduction mechanism 41b. It is changed to the high-speed low-torque drive (H gear) side that does not function.

  Further, the third ring gear 44c is restricted in its rotation by the ball 35 being locked by the urging force of the clutch spring 28a of the clutch mechanism 28. That is, when the load torque applied to the third ring gear 44c is lower than the engagement force between the ball 35 biased by the clutch spring 28a and the third ring gear 44c, the output of the speed reduction mechanism 41 is output to the output shaft 33. Transmitted to the side.

  On the other hand, when the load torque applied to the third ring gear 44c becomes higher than the engagement force between the ball 35 urged by the clutch spring 28a and the third ring gear 44c, the third ring gear 44c is moved to the clutch spring. The ball 35 is pushed back against 28a and idles. That is, when the third ring gear 44c idles, the output of the speed reduction mechanism 41 is not transmitted to the output shaft 33 side, and the output torque is mechanically limited. The mechanical limit of the output torque is set to a value sufficiently higher than the limit value of the controllable output torque by the control unit 71 (see FIG. 4) described later.

  As shown in FIG. 1, on the upper surface of the body portion 21 of the main body case 23, a shift changeover switch 36 for switching whether the speed reduction stage of the speed reduction mechanism 41 is fixed to any one of the predetermined speed stages or to perform the automatic speed change. Is provided. The speed change switch 36 is, for example, a slide switch, and by sliding its position in the front-rear direction, three drives of high speed low torque drive (H gear), low speed high torque drive (L gear), and automatic speed change (AUTO) are provided. It is a switch to switch to the mode. Further, a rotation direction changeover switch 37 for switching the rotation direction of the motor 25 is provided in the vicinity of the connection portion between the body portion 21 and the grip portion 22. The rotation direction changeover switch 37 is configured to be switchable to, for example, three states that cause the motor 25 to rotate forward, reverse, and stop. For example, the trigger switch 38 projects forward from the grip 22 in a state in which the trigger switch 38 is biased by a spring. 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, the battery pack mounting portion 22a accommodates a control portion 71 (see FIG. 4) that includes the motor 25 and performs overall control of the electric power tool 10.

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. 3, a handle attachment portion 61 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. In the handle attachment portion 61, the outer peripheral surface of the trunk portion 21 is recessed according to the shape of the attachment portion 51. The handle attachment portion 61 is provided with a pair of power supply terminals 62 formed along the outer peripheral surface of the trunk portion 21. Further, the handle attachment portion 61 is provided with a signal terminal 63 formed along the outer peripheral surface of the body portion 21 between the power supply terminals 62 in the front-rear direction.

  The attachment portion 51 of the auxiliary handle 12 includes a tightening portion 53 formed in a substantially columnar shape and an annular portion 54 extending from the side surface of the tightening portion 53. The annular portion 54 has a substantially annular shape formed in a direction orthogonal to the axial direction of the tightening portion 53. The attachment portion 51 is provided with a slit 57 across the tightening portion 53 and the annular portion 54, and the interval between the slits 57 can be changed in the axial direction of the tightening portion 53, that is, the diameter (inner diameter) of the annular portion 54 can be changed. It is like that. Further, a pair of power supply terminals 55 connected to the power supply terminal 62 of the handle mounting portion 61 and a signal terminal 56 connected to the signal terminal 63 are provided on the inner peripheral surface of the annular portion 54.

  The handle portion 52 is formed so as to extend along the axial direction of the tightening portion 53 and has an elongated and substantially cylindrical shape that can be easily held by the user's hand. A flange portion 52 a is provided on the proximal end side (attachment portion 51 side) of the handle portion 52. In the handle portion 52, a pressure sensor 58 is provided that outputs a detection signal corresponding to an external pressure, for example, a gripping force with which the user grips the handle portion 52. The pressure sensor 58 is connected to the power supply terminal 55 and the signal terminal 56 of the annular portion 54 via the wiring 59.

  Further, the auxiliary handle 12 is provided with a bolt (not shown) inserted in the axial direction in the tightening portion 53 and the handle portion 52, and both side portions separated by the slit 57 are connected by this bolt. For example, when the handle portion 52 is rotated, the space between the slits 57 can be changed by the action of a bolt that rotates with the handle portion 52.

  When attaching the auxiliary handle 12, the space between the slits 57, that is, the diameter of the annular portion 54, so that the annular portion 54 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 61. Is enlarged once. Then, the auxiliary handle 12 is fixed to the power tool main body 11 by performing tightening to reduce the interval between the slits 57 at the place where the annular portion 54 of the attachment portion 51 is disposed on the handle attachment portion 61. With this fixing, the power terminal 55 and the signal terminal 56 on the auxiliary handle 12 side and the power terminal 62 and the signal terminal 63 of the handle mounting portion 61 on the tool body 11 side are connected.

Next, electrical connection of the power tool 10 will be described.
As shown in FIG. 4, power is supplied from the battery pack 24 (not shown in FIG. 4) to the control unit 71 that performs output control of the electric power tool body 11, and a shift change switch 36, a rotation direction change switch 37, In addition, signals from various switches of the trigger switch 38 are input. With respect to the shift changeover switch 36, the control unit 71 controls the shift actuator 29 based on selection of the H gear, the L gear, and the automatic shift (AUTO) by the shift changeover switch 36. With respect to the rotation direction changeover switch 37, the control unit 71 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 37. With respect to the trigger switch 38, the trigger switch 38 outputs a signal corresponding to the pull-in amount, and the control unit 71 performs output control according to the pull-in amount.

  The control unit 71 receives a detection signal corresponding to the drive current supplied from the current detection unit 72 to the motor 25. The control unit 71 detects the load torque applied to the output shaft 33 based on the detection signal from the current detection unit 72. The control unit 71 controls the shift actuator 29 (automatic shift) when the motor 25 and automatic shift (AUTO) are selected based on the pull-in amount of the trigger switch 38 and the detected load torque, Output control is performed by both of them.

  Further, the control unit 71 determines whether the auxiliary handle 12 is attached to the electric tool body 11 by connecting the terminals 55 and 56 on the auxiliary handle 12 side and the terminals 62 and 63 on the electric tool body 11 side. Is going. In the mounted state of the auxiliary handle 12, a detection signal corresponding to the pressure value acting on the auxiliary handle 12 (handle unit 52) is input to the control unit 71 from the pressure sensor 58 provided on the auxiliary handle 12. The control unit 71 detects whether or not the user is holding the auxiliary handle 12 based on a detection signal corresponding to a pressure value acting on the auxiliary handle 12 (handle unit 52). When it is detected that the user is holding the auxiliary handle 12, the control unit 71 controls the motor 25 and the shift actuator 29 as usual. On the other hand, when it is detected that the user does not hold the auxiliary handle 12, the control unit 71 holds the gear shift actuator 29 on the high speed low torque (H gear) side so that high torque is not output. The output torque of the power tool 10 is limited.

Next, the operation (action) of the power tool 10 will be described.
As shown in the output characteristics of the electric tool 10 in FIG. 5, when operating with the high speed and low torque drive H gear, the output value changes on the straight line 81 and operates with the low speed and high torque drive L gear. If it is, the output value changes on the straight line 82. That is, in the case of high-speed and low-torque driving (H gear), the control unit 71 changes and holds the mode of the speed reduction mechanism 41 to H gear, and the output value on the straight line 81 is output by driving the motor 25. In the case of low-speed and high-torque driving (L gear), the control unit 71 changes and maintains the mode of the speed reduction mechanism 41 to L gear, and the output value on the straight line 82 is output by driving the motor 25. In the case of automatic transmission (AUTO), the mode of the speed reduction mechanism 41 is set to H gear at the start of driving, and the output value on the straight line 81 of high speed and low torque is output. When the load torque reaches “T1”, the mode of the speed reduction mechanism 41 is changed to the L gear, and automatic shift is performed so that the output value on the straight line 82 of low speed and high torque is output.

  In the automatic transmission mode, the control unit 71 detects (determines) whether the user is holding the auxiliary handle 12 (handle unit 52) during the operation of the electric power tool 10. When gripping by the user of the auxiliary handle 12 is detected, a normal automatic shift by the control unit 71 is performed. On the other hand, when it is detected that the auxiliary handle 12 is not gripped by the user, for example, it is determined that the power tool 10 is supported by only the grip portion 22 of the tool body 11 and the work is performed. Then, the high speed low torque drive (H gear) at the start of driving is maintained. That is, even when the load torque exceeds “T1” and a high torque is required, the shift to the low speed high torque drive (L gear) side is prohibited.

  In other words, when the speed reduction mechanism 41 is switched from the H gear to the L gear, the output torque of the electric tool 10 increases rapidly. Therefore, if the user does not fully anticipate this, the electric tool 10 at the time of switching or after the switching The recoil of is large and the supporting hand is shaken. In particular, when the electric power tool 10 is supported with one hand, there is a high possibility that the reaction from the electric power tool 10 cannot be handled. Therefore, if the auxiliary handle 12 is not gripped by the user during the operation of the trigger switch 38, switching from the H gear to the L gear side by the speed reduction mechanism 41 is prohibited, and the output torque is limited. ing. Note that switching from the L gear to the H gear side, that is, switching to a side where the output torque is reduced, is performed regardless of whether the auxiliary handle 12 (handle portion 52) is gripped.

This embodiment has the following effects.
(1) The auxiliary handle 12 is provided with a pressure sensor 58, and gripping by the user of the auxiliary handle 12 is detected by the control unit 71. When the control unit 71 detects that the user does not hold the auxiliary handle 12, the control unit 71 prohibits changing the reduction ratio of the power transmission unit 27 to the low speed high torque drive (L gear) side in the reduction mechanism 41. Then, the output torque of the electric tool 10 is limited. In other words, when the speed reduction mechanism 41 is switched from the H gear to the L gear, the output torque of the electric tool 10 increases rapidly. The recoil is large and the supporting hand is shaken. Especially in the case of one-hand support of the electric power tool 10, there is a high possibility that the electric tool 10 can not cope with the reaction from the electric power tool 10 due to switching to the L gear side. If not, switching to the L gear side is prohibited. 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) The significance of applying the above-described control to the present embodiment that is applied to the speed reduction mechanism 41 (power transmission unit 27) having two gear stages, that is, the output torque fluctuation when switching from the H gear to the L gear is large. large.

  (3) The auxiliary handle 12 can be attached to and detached from the electric tool main body 11. Whether the auxiliary handle 12 is attached to the electric tool main body 11 depends on whether the terminals 55 and 56 and the terminals 62 and 63 are connected to each other. Detected. When the control unit 71 detects that the auxiliary handle 12 is attached to the electric power tool body 11 by detecting the attachment / detachment, the control unit 71 detects gripping by the user of the auxiliary handle 12. Thereby, the grip detection of the auxiliary handle 12 can be performed more reliably.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the pressure sensor 58 is used to detect gripping of the auxiliary handle 12, but the present invention is not limited to this.

  For example, as shown in FIG. 6, a pressing switch 91 may be provided on the surface of the handle portion 52 of the auxiliary handle 12, and the switch 91 may be pressed as the user grips. In this case, the control unit 71 detects the presence or absence of gripping by the user of the auxiliary handle 12 based on the on / off signal from the push switch 91.

  Further, for example, as shown in FIG. 7, a temperature sensor 92 may be provided in the handle portion 52 of the auxiliary handle 12 to detect a temperature change caused by a user's grip or the like. In this case, the control unit 71 detects whether the user of the auxiliary handle 12 is gripped based on the temperature detection signal from the temperature sensor 92.

  In the above embodiment, the speed change mechanism 41 of the power transmission unit 27 has a two-stage shift speed. However, the speed change mechanism 41 may be applied to three stages or more, and further to a stepless speed change. In this case, the smaller the number of second and third gears, the greater the effect because the variation in output torque at the time of switching is greater.

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. However, the power tool 10 may be applied to another power tool with a shift.

  DESCRIPTION OF SYMBOLS 10 ... Electric tool, 11 ... Electric tool main body, 12 ... Auxiliary handle, 25 ... Motor, 27 ... Power transmission part, 33 ... Output shaft, 41 ... Deceleration mechanism (power transmission part), 58 ... Pressure sensor (gripping detection part) , 71 ... Control unit (torque detection unit, grip detection unit, attachment / detachment detection unit), 72 ... Current detection unit (torque detection unit), 91 ... Press switch (grip detection unit), 92 ... Temperature sensor (grip detection unit), T, T1 ... Torque.

Claims (3)

A motor, a power transmission unit configured to decelerate and transmit the rotational power of the motor to the output shaft and change its reduction ratio, a torque detection unit to detect a load torque applied to the output shaft, and the motor And an electric tool main body provided with an auxiliary handle for holding the electric power tool main body with respect to the electric power tool main body provided with a control unit that performs control to change the reduction ratio of the power transmission unit according to the detected load torque A tool,
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 prohibits changing the reduction ratio to the predetermined high torque side in the power transmission unit. An electric tool characterized by limiting output torque. The power tool according to claim 1,
The power transmission unit includes a plurality of reduction stages,
The control unit prohibits a change to a deceleration stage capable of outputting a predetermined high torque when the grip detection unit detects that the user is not gripping the auxiliary handle. Electric tool. In the electric tool according to claim 1 or 2,
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.