JP2014054707A - Electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric tool capable of suppressing unexpected change in a speed reduction ratio.SOLUTION: A control part 23 controls an actuator 27 for transmission in order to change a speed reduction ratio of a power transmission part 22 according to a detected load torque. The control part 23, when a ring gear RG (a cam member 30) is not in a target position (a first engaging position or a second engaging position) corresponding to the speed reduction ratio after the change of the speed reduction ratio, makes the cam member 30 rotate again by using the actuator 27 for transmission and slidably moves the ring gear RG.

Description

  The present invention relates to a power tool.

2. Description of the Related Art Conventionally, some electric tools control a power transmission unit that decelerates and transmits the rotational power of a motor by a control unit to automatically change a reduction ratio (see, for example, Patent Document 1).
In such an electric tool, for example, a load torque applied to an output shaft to which a tip tool (bit) is attached is detected from a load current (drive current) supplied to the motor, and the control unit is driven by the detected load torque. A control signal for changing the reduction ratio of the transmission unit is output to the gearshift actuator. When the speed reduction actuator changes to a predetermined value by driving the speed change actuator, the control signal from the control unit is stopped to stop the speed change actuator.

JP 2012-30347 A

  In the power tool as described above, after changing the reduction ratio, the gear shifting actuator is stopped. Therefore, the gear of the gear due to vibration during work or deterioration of machine parts, or the gear motor due to deterioration of the gear shifting actuator is stopped. There is a risk that the speed reduction ratio may deviate from a predetermined position depending on the amount of displacement due to inertial rotation until complete stop.

  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 suppress an unexpected change in the reduction ratio.

  In order to solve the above-described problem, the electric tool decelerates the rotational power of the motor and transmits it to the output shaft, and the power transmission unit configured to change the reduction ratio thereof, and the switching member is slid to move the power. A shift actuator that switches a reduction ratio of the transmission unit, a slide position detection unit that detects a slide position of the switching member, a torque detection unit that detects a load torque applied to an output shaft, and the load torque according to the detected load torque When the shift actuator is controlled to change the reduction ratio of the power transmission unit, and after changing the reduction ratio, the slide position detection unit is used to determine that the target position corresponding to the reduction ratio is not found And a control unit that controls the shift actuator so as to slide to the target position corresponding to the reduction ratio.

  Further, in the above configuration, when the control unit determines that the target position corresponding to the speed reduction ratio is not reached using the slide position detection unit, the control unit operates with the operating speed of the speed change actuator being slower than normal. It is preferable to control the shift actuator so as to slide to the target position corresponding to the reduction ratio.

  In the above configuration, when the control unit determines that the target position corresponding to the reduction ratio is not present using the slide position detection unit after changing the reduction ratio, the target position corresponding to the reduction ratio is determined. The shift actuator is controlled so as to slide to the next position, and when it is determined that the target position corresponding to the reduction ratio is not reached using the slide position detector after a predetermined time has elapsed, the shift actuator is driven. Is preferably stopped.

  In the above configuration, when the control unit determines that the target position corresponding to the reduction ratio is not found using the slide position detection unit after changing the reduction ratio, the control unit moves away from the target position. It is preferable to control the speed change actuator so that it is slid once to the target position corresponding to the reduction ratio.

In the above configuration, it is preferable that the slide position detection by the slide position detection unit is performed every predetermined time.
In the above configuration, when the control member slides the switching member using the speed change actuator, the control unit changes the slide speed of the switching member by the speed change actuator according to the slide position of the switching member. Is preferred.

  According to the present invention, the electric power tool can suppress an unexpected change in the reduction ratio.

It is a schematic block diagram of the electric tool in embodiment. It is a schematic block diagram of the electric tool in the same as the above. It is a top view of the automatic transmission of an electric tool same as the above. It is explanatory drawing for demonstrating the operation example of the electric tool in the same as the above. It is explanatory drawing for demonstrating the operation example of the electric tool of another example. It is explanatory drawing for demonstrating the operation example of the electric tool of another example. It is explanatory drawing for demonstrating the operation example of the electric tool of another example. It is explanatory drawing for demonstrating the operation example of the electric tool of another example.

  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 a battery pack 12 that can be attached to and detached from the power tool body 11. ing. The electric tool main body 11 includes a motor 21 that is driven based on the supply of driving power from the battery pack 12, a power transmission unit 22 that decelerates and outputs the rotational power of the motor 21, and the motor 21. And a control unit 23 for performing general control. The battery pack 12 has a secondary battery composed of a plurality of battery cells (for example, lithium ion batteries).

  As shown in FIG. 1, a power transmission unit 22 including a speed reduction mechanism, a clutch mechanism, and the like is connected to the rotating shaft 24 of the motor 21. The power transmission unit 22 decelerates the rotational power of the motor 21 and transmits it to the output shaft 25. The power transmission unit 22 includes, for example, two reduction gears (H gear and L gear), and moves any of the reduction gears by moving a ring gear RG (see FIG. 2) as a switching member in the axial direction of the output shaft 25. The gear ratio can be changed in two steps. In the present embodiment, the ring gear RG engages with the H gear at a relatively rear first engagement position indicated by a broken line in FIG. Note that when the ring gear RG is in the first engagement position, the high-speed rotation / low-torque mode has a relatively small reduction ratio.

  Further, the ring gear RG moves forward from the first engagement position, so that the engagement state with the H gear is released. Furthermore, the ring gear RG engages with the L gear when it moves to the second front engagement position indicated by a two-dot chain line in FIG. Note that when the ring gear RG is in the second engagement position, the low-speed rotation / high-torque mode has a relatively large reduction ratio.

  That is, in the present embodiment, when the ring gear RG slides from the first engagement position to the second engagement position, the power transmission unit 22 rotates at a high speed rotation with a low reduction ratio, and at a low speed rotation with a high reduction ratio from a low torque mode. Switch to high torque mode. On the other hand, when the ring gear RG slides from the second engagement position to the first engagement position, the power transmission unit 22 switches from the low speed rotation / high torque mode with a large reduction ratio to the high speed rotation / low torque mode with a small reduction ratio. .

  A tip tool (bit) 26 is attached to the tip of the output shaft 25. Accordingly, the electric power tool 10 is configured such that the tip tool 26 rotates together with the output shaft 25 when the rotational power of the motor 21 is decelerated by the power transmission unit 22 and transmitted to the output shaft 25.

  As shown in FIG. 1, the power transmission unit 22 is provided with a speed change actuator 27 for moving the ring gear RG to change the reduction ratio. The speed change actuator 27 is rotated by a speed change motor 27a that can rotate in both forward and reverse directions, a speed reduction portion 27b that transmits the drive power of the speed change motor 27a by decelerating, and a drive force that is transmitted via the speed reduction portion 27b. Output part 27c. As shown in FIG. 3, the output portion 27 c is an output gear and is engaged (engaged) with the cam member 30. As shown in FIG. 3, the cam member 30 includes a main body portion 31 that has an arc shape along the outer surface of the ring gear RG, and an engagement portion 35 that protrudes radially outward from the main body portion 31.

  As shown in FIG. 3, the main body 31 is formed with cam holes 31a and 31b that make a pair in the vicinity of both ends in the circumferential direction. The cam holes 31a and 31b include first and second holding portions 32a and 32b formed at positions shifted from each other in the axial direction and the circumferential direction of the output shaft 25, and the first and second holding portions 32a and 32b. And a connecting portion 32c to be connected. The engaging portion 35 is formed with a tooth-like engaging portion 35a that can mesh with the output portion 27c on the tip end side having an arc shape.

  As shown in FIG. 3, a cylindrical side wall of the gear case 22 a is disposed on the inner peripheral side of the main body 31 in the cam member 30. Further, the ring gear RG is accommodated in the gear case 22a. Further, a groove portion RGa having a concave shape in the radial direction along the circumferential direction is formed on the outer peripheral surface of the ring gear RG. A support member 51 is fitted in the groove RGa so as to be slidable with respect to the ring gear RG.

  As shown in FIG. 3, the support member 51 includes a pair of semi-circular support main body portions 52 that extend along the outer peripheral surface of the ring gear RG, and a pair of linearly extending radially outwards from both ends of the support main body portion 52. It has insertion parts 53a and 53b. The insertion portions 53a and 53b of the support member 51 are inserted from the inside into the through holes 22b forming the pair of gear cases 22a, and then inserted into the cam holes 31a and 31b forming the pair of the cam member 30.

  As shown in FIG. 3, when the output portion 27c meshes with a tooth portion on one end side (right end side in FIG. 3) of the tooth-like engagement portion 35a, the insertion portion 53a of the support member 51 holds the cam hole 31a second. Arranged in the portion 32b. On the other hand, the insertion portion 53b of the support member 51 is disposed in the second holding portion 32b of the cam hole 31b. At this time, the ring gear RG is disposed at the second engagement position (a relatively front position indicated by a two-dot chain line in FIG. 2), and the reduction ratio is set to the low speed rotation mode.

  When the output portion 27c rotates clockwise from the state shown in FIG. 3, the cam member 30 rotates counterclockwise. When the rotation angle of the output portion 27c reaches the predetermined rotation angle α1, the cam member 30 enters a state where the tooth portion on the other end side of the tooth-like engagement portion 35a is engaged with the output portion 27c. At this time, the insertion portion 53a of the support member 51 is disposed in the first holding portion 32a of the cam hole 31a. On the other hand, the insertion portion 53b of the support member 51 is disposed in the first holding portion 32a of the cam hole 31b. Further, as the cam member 30 rotates, the ring gear RG moves from the second engagement position to the first engagement position (a relatively rear position indicated by a broken line in FIG. 2), and the reduction ratio is low. Switch from rotation mode to high-speed rotation mode.

  The speed change actuator 27 includes a position detection unit 27d that detects the rotation amount of the output unit 27c. The position detection unit 27d detects the position of the ring gear RG in the sliding direction (the axial direction of the output shaft 25) according to this change because the resistance value changes according to the rotation angle (rotation amount) of the output unit 27c. Is to do.

  The speed change actuator 27 configured as described above operates by supplying drive power from the speed change drive unit 28 based on the control of the control unit 23. The speed change actuator 27 performs a switching operation of the speed reduction stage (deceleration gear) of the power transmission unit 22 based on the control of the control unit 23 via the speed change drive unit 28. Incidentally, the control unit 23 operates based on the supply of electric power that has undergone voltage adjustment from the battery pack 12. Further, the speed change drive unit 28 is configured by, for example, an H-bridge circuit using a switching element (for example, FET), and the control unit 23 determines the rotation direction of the speed change actuator 27 relative to the motor by a control signal for the speed change drive unit 28. Drive power supplied by PWM control is controlled.

  As shown in FIG. 1, the motor 21 is driven to rotate based on the supply of drive power generated by a switching drive circuit 29 including, for example, an H bridge circuit using a switching element (for example, FET). The switching drive circuit 29 controls the drive power supplied to the motor 21 from the power supplied from the battery pack 12 by PWM control by the control unit 23. That is, the control unit 23 controls the electric power supplied to the motor 21 via the switching drive circuit 29 and controls the rotation speed of the motor 21.

  As shown in FIG. 1, the power tool main body 11 is provided with a trigger switch Tr that can be operated by a user. The trigger switch Tr includes ON / OFF for starting and stopping the motor 21, and outputs an output signal corresponding to the operation amount (trigger pull-in amount) of the trigger switch Tr to the control unit 23. And the control part 23 controls the electric power supplied to the motor 21 in the switching drive circuit 29 based on the output signal from the trigger switch Tr, and starts and stops the motor 21 and adjusts the rotational speed during operation. .

  As shown in FIG. 1, a current detection unit 41 for detecting a drive current supplied to the motor 21 is provided between the switching drive circuit 29 and the motor 21. The current detection unit 41 includes a detection resistor 42 connected between the switching drive circuit 29 and the motor 21, and an amplification circuit (op-amp) that amplifies the terminal voltage of the detection resistor 42 and outputs it as a detection signal to the control unit 23. 43. The control unit 23 detects the drive current based on the detection signal from the current detection unit 41 at every predetermined sampling time, and based on the detected drive current and the deceleration stage of the power transmission unit 22 when the drive current is detected. A load torque applied to the output shaft 25 (tip tool 26) is detected. Further, the control unit 23 detects the lock of the motor 21 based on the detected load torque and controls the motor 21.

  As shown in FIG. 1, the rotation shaft 24 of the motor 21 is provided with a rotation detector 61 for detecting the rotation speed of the motor 21. The rotation detection unit 61 includes a sensor magnet 62 that is fixed to the rotation shaft 24 so as to be integrally rotatable and has a plurality of magnetic poles, and a Hall element 63 that is disposed to face the sensor magnet 62. The hall element 63 outputs a change in magnetic flux based on the rotation of the sensor magnet 62 to the control unit 23 as a detection signal. The control unit 23 detects the rotation speed of the motor 21 based on the detection signal from the rotation detection unit 61. Further, the control unit 23 detects the lock of the motor 21 also by this change in the rotational speed.

  As shown in FIG. 1, the electric tool 10 is configured such that automatic shift is performed by the control unit 23 switching and controlling the deceleration stage of the power transmission unit 22 through the shift actuator 27 based on the detected load torque. Yes. Note that the speed reduction mechanism of the power transmission unit 22 is, for example, a planetary gear speed reduction mechanism, and a sun gear that is driven to rotate about the axis of the rotation shaft 24 of the motor 21 and a planetary gear that is arranged around and meshed with the sun gear. And a ring gear RG meshed with the planetary gear. The speed change actuator 27 can control the speed reduction stage by changing the position of the ring gear and changing the planetary gear meshing with the ring gear. Further, the speed change actuator 27 is controlled based on the detection signal of the position detection unit 27d for detecting whether the ring gear has been changed to the correct position by the speed change actuator 27.

  In the electric power tool 10 configured as described above, when the trigger switch Tr is pulled in by the user, an output signal corresponding to the pull-in amount is input to the control unit 23. The control unit 23 controls the switching drive circuit 29 based on the output signal from the trigger switch Tr, and the start / stop and rotation speed of the motor 21 are controlled. The tip tool 26 rotates as the rotational power of the motor 21 is decelerated by the power transmission unit 22 and transmitted to the output shaft 25. Further, the control unit 23 changes the deceleration stage of the power transmission unit 22 to either the H / L gear according to the load torque. In this case, when the load torque is small, the H transmission is selected by the power transmission unit 22, and the tip tool 26 is driven at high speed rotation and low torque. At the time of activation, the H transmission is selected in the power transmission unit 22. When the load torque increases and exceeds the predetermined torque, the power transmission unit 22 selects the L gear, and the tip tool 26 is driven at a low speed and a high torque. In addition, the control unit 23 detects the lock of the motor 21 based on the detection signals from the rotation detection unit 61 and the current detection unit 41 and performs control to stop the motor 21.

Next, an operation example (action) of shifting (changing the reduction ratio) of the electric tool will be described.
As shown in FIGS. 1 to 4, when the speed change condition is satisfied at a certain time t <b> 0, the controller 23 slides the ring gear RG by driving the speed change actuator 27 and rotating the cam member 30. Let Thereby, the ring gear RG is switched from the H gear to the L gear, and the reduction ratio is changed. Then, for example, when the output unit 27c is rotated by the predetermined rotation angle α1 by the position detection unit 27d at the time t1 and reaches the target position, the control unit 23 stops the speed change actuator motor and ends the speed change operation.

  Here, when there is no brake function (the function of stopping the motor immediately when the power is shut off by a regenerative diode or the like), the speed change motor 27a of the present embodiment rotates by inertia even after the power supply is cut off. For this reason, the cam member 30 continues to rotate by the inertia rotation. When the second holding portion 32b of the cam member 30 and the insertion portion 53a (53b) of the support member 51 collide with each other due to this inertia, the reaction moves in a direction opposite to a predetermined direction (time t2). Further, for example, the position of the speed change cam plate deviates from a predetermined position due to vibration during operation.

  For this reason, the control unit 23 acquires the signal of the position detection unit 27d after a predetermined time has elapsed (time t3) from the end of the shift operation (time t1), and when the shift actuator 27 is out of the predetermined position, By driving the motor 27a, the cam member 30 is rotated to slide the ring gear RG to a predetermined position (time t4). At this time, the control unit 23 changes the duty ratio of the motor 27a of the speed change actuator 27 so as to be slower than the normal speed change operation. Then, when the cam member is rotated and the ring gear RG reaches a predetermined position, the control unit 23 stops driving the motor 27a of the transmission actuator 27 and ends the control of the transmission actuator 27.

Next, the effect of this embodiment will be described.
(1) The control unit 23 controls the shift actuator 27 to change the reduction ratio of the power transmission unit 22 according to the detected load torque. If the ring gear RG (cam member 30) is not present at the target position (first engagement position or second engagement position) corresponding to the reduction ratio after the reduction ratio is changed, the control unit 23 changes the speed change actuator 27. Is used to rotate the cam member 30 again to slide the ring gear RG. For this reason, an unexpected change in the reduction ratio after the reduction ratio change can be suppressed.

  (2) When the control unit 23 determines that the target position corresponding to the speed reduction ratio is not reached using the position detection unit 27d, the control unit 23 sets the speed reduction ratio in a state where the operation speed of the speed change actuator 27 is slower than normal. Slide to the corresponding target position. For this reason, for example, after the power supply to the speed change motor 27a is interrupted, the inertial rotation amount can be suppressed even without the brake function. For this reason, the amount of movement when moving in the direction opposite to the predetermined direction due to the reaction when the second holding portion 32b of the cam member 30 collides with the insertion portion 53a (53b) of the support member 51 due to inertia is suppressed. Can do.

In addition, you may change the said embodiment as follows.
Although not specifically mentioned in the above embodiment, the following control examples may be added as appropriate.
As shown in FIG. 5, when the control unit 23 determines that the target position corresponding to the reduction ratio is not reached using the position detection unit 27d after changing the reduction ratio (t5), the target corresponding to the reduction ratio is set. The shift actuator 27 (motor 27a) is controlled to slide to the position. Thereafter, if the control unit 23 determines that the target position corresponding to the reduction ratio is not reached by using the position detection unit 27d after a predetermined time has elapsed (time t6), the control actuator 23 (motor 27) Stop driving. By adopting such a configuration, it is possible to reduce the risk of failure of the speed change actuator 27 and the power transmission unit 22 because the operation is stopped without forcibly sliding to the target position.

  As shown in FIG. 6, the control unit 23 may be configured to perform slide position detection by the position detection unit 27 d at predetermined time intervals. Thus, by performing a plurality of position detections of the ring gear RG, if the ring gear RG deviates from the target position, it can be slid to the target position each time.

  As shown in FIG. 7, when the control unit 23 determines that the target position corresponding to the reduction ratio is not reached using the position detection unit 27d after changing the reduction ratio, the control unit 23 temporarily moves away from the target position. The slide is moved (time t7). Thereafter, the control unit 23 controls the speed change actuator 27 so as to slide to the target position corresponding to the reduction ratio (time t8).

  When sliding the ring gear RG, the control unit 23 may change the slide speed (moving speed) of the ring gear RG by the shift actuator 27 according to the slide position of the ring gear RG as the switching member. For example, as shown in FIG. 8, when the speed change condition is satisfied at a certain time t <b> 10, the control unit 23 drives the speed change actuator 27 (motor 27 a) to rotate the cam member 30. Then, the control unit 23 drives the motor 27a with a duty ratio of 100% until time t11. Thereafter, the control unit 23 drives the motor 27a with a duty ratio of 80% until time t12. Thereafter, the control unit 23 drives the motor 27a with a duty ratio of 60% until time t13. Then, the control unit 23 drives the motor 27a with a duty ratio of 40% until the time t4 when the shift is completed. When the shift is completed (time t4), the control unit 23 stops driving the motor 27a. In this way, the driving speed (rotational speed) of the motor 27a is gradually reduced after the start of shifting, and the moving speed (sliding speed) of the ring gear RG as the switching member is reduced. By setting it as such a structure, the movement amount at the time of moving to a direction opposite to a predetermined direction by reaction when the cam member 30 and the support member 51 collide by inertia can be suppressed.

  In the above embodiment, after shifting from the H gear to the L gear (changing the reduction gear ratio), the position of the ring gear RG is detected, and the second engagement is detected when it is not at the second engagement position that is the target position. Although the ring gear RG is slid to the position, the present invention is not limited to this. For example, after shifting from the L gear to the H gear (changing the reduction ratio), if the position of the ring gear RG is detected and the ring gear RG is not at the first engagement position, which is the target position, the ring gear is moved to the first engagement position. The RG may be slid.

-In above-mentioned embodiment, although the power transmission part 22 was set as the structure which switches two reduction ratios, it is good also as a structure which switches three or more reduction ratios automatically.
In the above embodiment, the speed change actuator 27 is a motor actuator. However, the motor is not limited to a motor, and a solenoid or the like may be used.

In the above embodiment, the lock detection is performed, but may be omitted.
In the above embodiment, the power tool 10 is embodied as a drill driver, but other power tools such as an impact driver, an impact wrench, a hammer drill, a vibration drill, a jigsaw, and a sealing gun may be used.

  DESCRIPTION OF SYMBOLS 10 ... Electric tool, 21 ... Motor, 22 ... Power transmission part, 23 ... Control part, 25 ... Output shaft, 27 ... Shifting actuator, 27a ... Motor which comprises a shifting actuator, 27d ... Position as a slide position detection part Detection part, 41 ... Current detection part (torque detection part), RG ... Ring gear as switching member, T ... Load torque.

Claims (6)

A power transmission unit configured to decelerate and transmit the rotational power of the motor to the output shaft and to change its reduction ratio;
A shifting actuator that slides the switching member to switch the reduction ratio of the power transmission unit;
A slide position detector for detecting a slide position of the switching member;
A torque detector for detecting a load torque applied to the output shaft;
The shift actuator is controlled to change the reduction ratio of the power transmission unit according to the detected load torque, and the target position corresponding to the reduction ratio is changed using the slide position detection unit after changing the reduction ratio. And a control unit that controls the shift actuator so as to slide to the target position corresponding to the reduction ratio. The power tool according to claim 1,
When the control unit determines that the target position corresponding to the reduction ratio is not reached using the slide position detection unit, the control unit corresponds to the reduction ratio in a state where the operation speed of the speed change actuator is slower than normal. The power tool, wherein the shift actuator is controlled to slide to the target position. In the electric tool according to claim 1 or 2,
If the control unit determines that the target position corresponding to the reduction ratio is not present using the slide position detection unit after changing the reduction ratio, the control unit slides to the target position corresponding to the reduction ratio. The shift actuator is controlled, and after a predetermined time has elapsed, when it is determined that the target position corresponding to the reduction ratio is not reached using the slide position detection unit, the drive of the shift actuator is stopped. A power tool. In the electric tool according to any one of claims 1 to 3,
When the control unit determines that the target position corresponding to the reduction ratio is not found by using the slide position detection unit after changing the reduction ratio, the control unit is once slid in a direction away from the target position. The power tool is characterized in that the shift actuator is controlled to slide to the target position corresponding to the reduction ratio later. In the electric tool according to any one of claims 1 to 4,
A power tool, wherein the slide position is detected by the slide position detector at predetermined time intervals. In the electric tool according to any one of claims 1 to 5,
The control unit is configured to change the slide speed of the switching member by the shifting actuator according to the slide position of the switching member when the switching member is slid using the shifting actuator. tool.