TWI803064B - Electric tool and control method thereof - Google Patents

Abstract

An electric tool, comprising a motor, a reduction mechanism, a drive shaft, a torque sensing module, a driving device and a control device, wherein the reduction mechanism is coupled between the motor and the drive shaft; the torque sensing module Sensing the torque on the driving shaft; the driving device is used to drive the motor to run. The control method includes: the control device operates in a first rotation mode to output a first driving signal to the driving device, so that the driving device drives the motor to rotate so that the rotating shaft rotates in a first rotation direction, and judges the torque sensing module When the sensed torque rises to a first predetermined torque, the driving device gradually reduces a running current of the motor within the first predetermined period, and judges that when the torque sensed by the torque sensing module drops to a second predetermined torque, Stop the motor from running.

Description

Electric tool and control method thereof

The invention relates to electric tools; in particular, it refers to an electric tool without a clutch mechanism and a control method thereof.

Traditional electric tools, such as an electric torque driver without a clutch mechanism, or an electric torque wrench, allow users to set the torque, and lock screws, nuts and other workpieces according to the torque set by the user. When the torque of locking the workpiece reaches the torque set by the user, the motor of the electric tool stops rotating immediately. In this way, the workpiece can be locked to the torque set by the user.

However, during the process of locking the workpiece, the user must apply force to resist the rotational force generated by the electric tool when holding the electric tool, so as to maintain the stability of holding the electric tool. However, when the torque of locking the workpiece reaches the torque set by the user, the moment the motor stops rotating, the rotational force generated by the electric tool has disappeared instantly, so the force exerted by the user will form an inertial force, causing the wrist It can twist, causing discomfort in use, and worse, a sprained wrist.

In addition, when disassembling a locked workpiece, the user must apply force to resist the rotational force generated by the electric tool when holding the electric tool. Since the motor of the electric tool is driven at a high speed, the workpiece is still locked. In the state, the actual speed of the motor is limited by the locked workpiece and cannot be increased to a high speed. But at the moment when the workpiece is unscrewed, the unscrew produced by the electric tool The turning force has disappeared instantly, which will also cause the force exerted by the user to form an inertial force, causing the wrist to twist.

Therefore, the design of traditional power tools is still not perfect, and there is room for improvement.

In view of this, the purpose of the present invention is to provide an electric tool and a control method thereof, which can avoid the discomfort caused by the user when using the electric tool to lock the workpiece.

Another object of the present invention is to provide an electric tool and its control method, which can avoid the discomfort caused by the user when using the electric tool to disassemble the workpiece.

In order to achieve the above object, the present invention provides an electric tool, which includes a motor, a speed reduction mechanism, a drive shaft, a torque sensing module, a drive device and a control device, wherein the motor has a shaft; the The deceleration mechanism has an input end and an output end, the input end is connected to the rotating shaft of the motor; the drive shaft is connected to the output end of the deceleration mechanism; the torque sensing module senses a torque on the drive shaft; the The drive device is electrically connected to the motor and is used to drive the motor to run; the control device is electrically connected to the drive device and the torque sensing module, and the control device is operable in a first rotation mode. mode, the control device outputs a first drive signal to the drive device, so that the drive device drives the motor to rotate so that the shaft rotates in a first rotation direction, and the control device judges the torque sensed by the torque sensing module When the torque rises to a first predetermined torque, the control device outputs a second drive signal to the drive device within a first predetermined period, so that the drive device gradually reduces a torque of the motor within the first predetermined period. When the control device judges that the torque sensed by the torque sensing module drops to a second predetermined torque, it stops outputting the second driving signal to the driving device, so that the driving device stops the motor from running.

The present invention also provides a control method of an electric tool, which is executed by the control device, and includes the following steps: A. Operate in a first rotation mode; output a first driving signal to the driving device, so that the driving device drives the The motor runs so that its shaft rotates along a first rotation direction; B. When judging that the torque sensed by the torque sensing module rises to a first predetermined torque, output a second drive signal to the Drive device, so that the drive device gradually reduces an operating current of the motor within the first predetermined period; C. When judging that the torque sensed by the torque sensing module drops to a second predetermined torque, stop outputting the first Two driving signals are sent to the driving device to make the driving device stop the motor from running.

In this way, when the locking workpiece reaches the first predetermined torque set by the user, the motor will gradually reduce the torque to the second predetermined torque before stopping, which can effectively reduce the inertial force on the user's hand and prevent the user from discomfort.

Wherein, the control device is operable in a second rotation mode, and in the second rotation mode, the control device outputs a third driving signal to the driving device, and the third driving signal includes a control signal of a first rotational speed , so that the driving device drives the motor according to the first rotational speed so that the rotating shaft generates a rotational force along a second rotational direction, wherein the second rotational direction is opposite to the first rotational direction, and the control device judges that the When the torque sensed by the torque sensing module rises to a third predetermined torque and then decreases, the control device outputs a fourth drive signal to the drive device within a second predetermined period, the fourth drive signal includes a rotational speed increase The control signal is used to make the driving device drive the motor to rotate in a manner of gradually increasing the rotational speed so that the rotating shaft continues to generate rotational force along the second rotational direction.

In this way, when disassembling the workpiece in the locked state, firstly drive the motor at a lower first speed, and then gradually increase the speed to the highest speed when the workpiece is loosened, which can effectively reduce the inertial force on the user's hand , to avoid user discomfort.

1,2: Electric tools

10: Shell

12:Handheld part

14: Transmission department

20: motor

22: Shaft

30:Deceleration mechanism

302: input terminal

304: output terminal

40: drive shaft

42: Tool head

50:Torque sensing module

60: drive device

62: Driver circuit board

64: commutation switch element

66: Hall sensor

68: Controller

70: Control device

72: First control device

722: The first circuit board

724: first controller

74: Second control device

742: Second circuit board

744: second controller

80: battery

82: Operation interface

822: start switch

824: Steering switch

826: Torque setter

90: Current detection module

D1: the first direction of rotation

D2: Second direction of rotation

Fig. 1 is a schematic diagram of an electric tool according to a first preferred embodiment of the present invention.

Fig. 2 is a system block diagram of the electric tool according to the first preferred embodiment of the present invention.

FIG. 3 is a flow chart of the control method of the electric tool used to lock the workpiece according to the first preferred embodiment of the present invention.

FIG. 4 is a curve of the torque sensed by the torque sensing module of the first preferred embodiment of the present invention.

FIG. 5 is a flow chart of the control method of the electric tool used for removing workpieces according to the first preferred embodiment of the present invention.

FIG. 6 is a curve of torque sensed by the torque sensing module and a curve of rotation speed according to the first preferred embodiment of the present invention.

FIG. 7 is a curve of torque sensed by the torque sensing module and a curve of rotational speed according to the second preferred embodiment of the present invention.

FIG. 8 is a system block diagram of an electric tool according to a third preferred embodiment of the present invention.

9 is a curve of torque sensed by the torque sensing module and a curve of predetermined current according to the third preferred embodiment of the present invention.

FIG. 10 is a curve of the torque sensed by the torque sensing module and a curve of the predetermined torque according to the fourth preferred embodiment of the present invention.

In order to illustrate the present invention more clearly, preferred embodiments are given and detailed descriptions are given below in conjunction with drawings. Please refer to Fig. 1 and Fig. 2, which is an electric tool 1 according to the first preferred embodiment of the present invention, including a housing 10, a motor 20, a reduction mechanism 30, a drive shaft 40, and a torque sensing module 50 . A driving device 60 and a control device 70 .

The casing 10 has a handle portion 12 and a transmission portion 14 in this embodiment. The handle portion 12 is combined under the transmission portion 14 , and the handle portion 12 and the transmission portion 14 have a long axis. The handle 12 is for the user to hold and has a battery 80 at the bottom.

The motor 20 is disposed on the transmission part 14 and has a rotating shaft 22 . In this embodiment, the motor 20 is a three-phase DC brushless motor.

The reduction mechanism 30 has an input end 302 and an output end 304 , and the input end 302 is connected to the rotating shaft 22 of the motor 20 . The reduction mechanism 30 can be, for example, a planetary gear reducer.

One end of the drive shaft 40 is connected to the output end of the speed reduction mechanism 30 , and the other end is provided with a tool head 42 . The drive shaft 40 and the speed reduction mechanism 30 are directly driven without transmission through a clutch mechanism. The tool head 42 is used to rotate a workpiece, such as a screw or nut. For example, the tool head 42 can be, for example, a hexagon socket, a hexagon socket, a cross, or a slotted tool head 42 for driving and turning a hexagon socket socket, an external hexagon socket, a cross, or a slotted screw.

The torque sensing module 50 senses the torque on the drive shaft 40. In this embodiment, the torque sensing module 50 is set on the drive shaft 40 as an example, but it is not limited thereto. It can be arranged at any position that can sense the torsion force on the drive shaft 40 to indirectly sense the torsion force on the drive shaft 40 , such as on the reduction mechanism 30 .

The driving device 60 is electrically connected to the motor 20 and used to drive the motor 20 to run. In this embodiment, the driving device 60 includes a driving circuit board 62, and a plurality of commutation switch elements 64, a plurality of Hall sensors 66 and a controller arranged on the driving circuit board 62 68, wherein the controller 68 can be a microcontroller, the controller 68 is electrically connected to the commutation switch elements 64 and the Hall sensors 66, and the commutation switch elements 64 are in this embodiment There are six MOSFETs and are electrically connected to the stator of the motor 20. The Hall sensors 66 are three and are used to sense the position of the rotor of the motor 20 respectively. The output of each Hall sensor 66 is at A voltage level and a second voltage level are switched, and the Hall sensors respectively output pulse waves sequentially when the rotor rotates 120 degrees to form a position signal in the form of pulse waves. The battery 80 is electrically connected to the driving circuit board 62 to provide the power required by the driving device 60 and the motor 20 .

The controller 68 judges the angle of the rotor according to the position signal and controls the phase change switch elements 64 to drive the motor so that the motor shaft rotates in a first direction of rotation D1 or a second direction of rotation D2, and can The rotational speed of the rotating shaft 22 is controlled. The second rotation direction D2 is opposite to the first rotation direction D1.

The control device 70 is electrically connected to the torque sensing module 50 and the driving device 60 , and the control device 70 is further connected to the battery 80 and an operation interface 82 . The control device 70 is operable in a first rotation mode or a second rotation mode, wherein the first rotation mode is used to control the driving device 60 to drive the shaft 22 of the motor 20 to rotate along the first rotation direction D1 , used for locking the workpiece; the second rotation mode is used to control the driving device 60 to drive the rotating shaft of the motor 20 to rotate along the second rotation direction D2 for disassembling the workpiece.

In this embodiment, the control device 70 includes a first control device 70 and a second control device 70 , and the first control device 70 includes a first circuit board 722 and a first controller 724 . The first circuit board 722 is electrically connected to the battery 80 to receive power from the battery 80 , and is electrically connected to the driving device 60 and the torque sensing module 50 .

The second control device 70 includes a second circuit board 742 and a second controller 744, the second circuit board 742 is electrically connected to the first circuit board 722 and the operation interface 82, so as to Power is received from the first circuit board 722 and an operation command is sent from the second controller 744 to the first controller 724 .

The operation interface 82 is electrically connected to the second control device 70 and includes a start switch 822, a steering switch 824 and a torque setting device 826. The start switch 822 is operated by the user to output a start signal to the second control device 70 , the steering switch 824 is operated by the user to switch the forward rotation state or the reverse rotation state, and then output a steering signal to the second control device 70, the steering signal is one of a forward rotation signal and a reverse rotation signal . The torque setter 826 is for the user to set a torque required for locking the workpiece (ie a first predetermined torque), and the first predetermined torque set by the second controller 744 is transmitted to the first controller 724 . The second controller 744 generates the operation command corresponding to the forward rotation signal or the reverse rotation signal according to the start signal and the steering signal, and sends it to the first controller 724 .

The first controller 724 operates in the first rotation mode or the second rotation mode according to the operation command, and when the operation command received by the first controller 724 corresponds to the forward rotation signal, the first controller 724 Operates in the first rotation mode; when the operation command received by the first controller 724 corresponds to the reverse signal, the first controller 724 operates in the second rotation mode.

The steps of the control method of this embodiment for locking the workpiece will be described later, which includes the following steps shown in FIG. 3 .

The user switches the steering switch 824 to the forward rotation state, presses the tool head 42 against the workpiece, and after pressing the start switch 822, the first controller 724 operates in the first rotation mode and outputs a first drive The signal is sent to the driving device 60 , so that the driving device 60 drives the motor 20 to rotate the rotating shaft 22 along the first rotating direction D1 . In this embodiment, the first drive signal includes a direction control signal and a speed control signal, and the controller 68 of the driving device 60 controls the commutation switch elements 64 according to the direction and speed control signals, so that the The shaft 22 of the motor 20 rotates. At this time, the rotating shaft is decelerated by the speed reducing mechanism 30 to drive the driving shaft 40 to rotate clockwise at a relatively low speed, so as to drive the workpiece to rotate. As shown in Figure 4, the torque sensed by the torque sensing module 50 gradually increases from 0 Nm, and in the process of gradually locking the workpiece, the torque received by the drive shaft 40 is gradually increased due to the gradual increase in the resistance of the workpiece. It also increases accordingly, therefore, the torque sensed by the torque sensing module 50 gradually increases.

Continue referring to FIG. 4, the first controller 724 judges the torque sensed by the torque sensing module 50 according to the output result of the torque sensing module 50, and when the sensed torque rises to the first predetermined torque, it means Having locked the workpiece, the first controller 724 outputs a second driving signal to the driving device 60 within a first predetermined period, so that the driving device 60 gradually reduces a speed of the motor 20 within the first predetermined period. operating current. As the operating current of the motor 20 decreases gradually, the output torque of the motor 20 decreases gradually, and the torque received by the drive shaft 40 also decreases accordingly.

When the first controller 724 judges that the torque sensed by the torque sensing module 50 drops to a second predetermined torque, it stops outputting the second driving signal to the driving device 60 so that the driving device 60 stops the motor 20 from running. , and the shaft stops rotating. In this embodiment, the second predetermined torque is 0 Nm as an example, but it is not limited thereto. The second predetermined torque can be less than half or one-third of the first predetermined torque to more than 0 Nm.

In this way, when the locking workpiece reaches the first predetermined torque set by the user, the motor 20 will gradually reduce the torque to the second predetermined torque before stopping, so the inertial force on the user's hand can be effectively reduced. In this embodiment, the first predetermined period (that is, the time for the torque sensed by the torque sensing module to drop from the first predetermined torque to the second predetermined torque) is more than 100 milliseconds, and the longer the first predetermined period, the user The less inertial force the hand is subjected to. Considering the operation efficiency, the first predetermined period is set to be 100-150 milliseconds.

The above is the steps of the control method of this embodiment for locking the workpiece, and then the steps of the control method of this embodiment for dismounting the workpiece will be described, which includes the following steps shown in FIG. 5 .

The user switches the steering switch 824 to the reverse state, presses the tool head 42 against the workpiece, and after pressing the start switch 822, the first controller 724 operates in the second rotation mode and outputs a third driving mode. signal to the driving device 60, the third driving signal includes a control signal of a first rotational speed, so that the controller of the driving device 60 drives the motor 20 to rotate according to the first rotational speed so that the rotating shaft 22 generates along the second rotation The rotational force in the direction D2, wherein the first rotational speed is, for example, 50 rpm. As shown in FIG. 6 , since the workpiece is in a locked state, the workpiece cannot be rotated at this time. Therefore, the torque sensing module 50 can sense the torque generated on the drive shaft 40 . The direction of the torsion force generated when the workpiece is disassembled is opposite to the direction of the torsion force generated when the workpiece is locked. In this embodiment, the third driving signal is to make the driving device gradually increase from the first rotating speed to a second rotating speed to drive the motor to run, and the second rotating speed is, for example, 100 rpm. For example, the first rotational speed is gradually increased to the second rotational speed linearly with a positive slope.

Continuing to refer to Fig. 6, when the first controller 724 of this control device 70 judges that the torque sensed by the torque sensing module 50 rises to a third predetermined torque and then drops, it means that the workpiece has begun to loosen, then the first controller 724 Output a fourth driving signal to the driving device 60 within a second predetermined period, wherein the fourth driving signal includes a control signal for increasing the speed, so that the driving device 60 drives the motor 20 to run in a manner of gradually increasing the speed Make its rotating shaft 22 continue to generate the rotating force along the second rotating direction. The second predetermined period may be, for example, 100-200 milliseconds. At the beginning of the second predetermined period, the rotational speed starts to increase from a second rotational speed (for example, 100 rpm). If the rotational speed has not yet reached the set second rotational speed when the torque rises to a third predetermined torque, the rotational speed is increased from the current rotational speed at the beginning of the second predetermined period. Or, if the torque rises before reaching a third preset torque, the rotating speed has reached the preset When the second rotation speed is fixed, it is maintained at the second rotation speed. When the torque rises to the third predetermined torque and then decreases, the rotation speed increases from the second rotation speed at the beginning of the second predetermined period.

In this embodiment, the control signal for increasing the rotational speed of the fourth driving signal within the second predetermined period makes the driving device 60 gradually increase from the second rotational speed to a third rotational speed (i.e., the target rotational speed) to drive the motor 20 to run, For example, gradually increase from the second rotational speed to the third rotational speed linearly with a positive slope, but not limited thereto, the rotational speed can also be increased non-linearly, and at the end of the second predetermined period or the torque sensing When the torque sensed by the module 50 drops to 0 Nm, the rotation speed is maintained at the third rotation speed until the user releases the start switch 822 . The third rotational speed may be, for example, more than five times of the first rotational speed. Taking six times as an example, the third rotational speed is 300 rpm.

In this way, when disassembling a workpiece in a locked state, firstly drive the motor 20 at a lower first rotational speed, and then gradually increase the rotational speed to the highest third rotational speed (target rotational speed) when the workpiece is loosened, so as to quickly unscrew the workpiece , It can avoid the inertia force caused by directly dismantling the workpiece in the locked state at high speed to make the user's hand feel uncomfortable.

In a second preferred embodiment, as shown in FIG. 7 , the first rotational speed can also be maintained before the sensed torque rises to a third predetermined torque. When the second predetermined period begins, the rotational speed changes from the first rotational speed Start increasing to target speed.

What is shown in FIG. 8 is the electric tool 2 of the third preferred embodiment of the present invention, which is based on the structure of the first embodiment, and further includes a current detection module 90, electrically connected to the motor 20 and the control The device 70 detects the operating current of the motor 20 . In this embodiment, the current detection module 90 is disposed on the driving circuit board 62 of the driving device 60 and electrically connected to the first controller of the control device 70 .

As shown in FIG. 9 , the control device 70 is based on the change relationship of a predetermined current relative to time and the operating current detected by the current detection module 90 within the first predetermined period. Comparing and outputting the second driving signal, the change of the operating current of the motor 20 within the first predetermined period can conform to the change relationship of the predetermined current relative to time, so that the degree of reduction of the torque of the motor 20 is easier to control. The change relationship of the predetermined current with respect to time can be stored in the memory of the first controller 724 . The change relationship of the predetermined current with respect to time is a linear change with a negative slope, and the negative slope is proportional to the first predetermined torque, that is, the higher the first predetermined torque set by the user, the absolute value of the negative slope The larger the value. In an embodiment, the change relationship of the predetermined current with respect to time may also be a non-linear change, such as a curve or step decrease.

More specifically, the first controller 724 of the control device 70 acquires the detected operating current at intervals of a sampling time during the first predetermined period, and the change of the predetermined current relative to time is related to any The sampling time has a corresponding current value. When the operating current detected by the first controller 724 of the control device 70 at any sampling time is greater than the current value of the corresponding predetermined current, the second drive output by the first controller 724 of the control device 70 The signal includes a current reduction signal to make the driving device 60 reduce the operating current of the motor 20 . The first controller 724 of the control device 70 at any one of the sampling time, when the detected operating current is less than the current value of the corresponding predetermined current, the second output of the first controller 724 of the control device 70 The driving signal includes a current boost signal to make the driving device 60 increase the running current of the motor. Thereby, the variation of the operating current of the motor 20 within the first predetermined period can conform to the variation relationship of the predetermined current with respect to time.

With the change relationship of the predetermined current relative to time and the detected running current of the motor 20, the running current can be controlled more accurately to decrease, avoiding too fast or too slow, so that the torque drop can be controlled more accurately.

In a fourth preferred embodiment, it is based on the structure of the second embodiment, the difference is that the operating current is controlled by the change of the sensed torque, and then the torque is reduced. More specifically, as shown in FIG. 10 , the control device 70 in the first predetermined period according to The change relationship of a predetermined torque relative to time is compared with the torque sensed by the torque sensing module 50 to output the second drive signal, so that the change of torque within the first predetermined period can conform to the change of predetermined torque relative to time The relationship makes the degree of reduction of the torque of the motor 20 easier to control. The change relationship of the predetermined torque with respect to time can be stored in the memory of the first controller 724 . The change relationship of the predetermined torque with respect to time is a linear change with a negative slope, and the negative slope is proportional to the first predetermined torque, that is, the higher the first predetermined torque set by the user, the absolute value of the negative slope The larger the value. In an embodiment, the change relationship of the predetermined torque with respect to time may also be a nonlinear change, such as a curve or step decrease.

The first controller 724 of the control device 70 obtains the torque sensed by the torque sensing module 50 every other sampling time within the first predetermined period, and the change of the predetermined torque relative to time is related to any one of the sampling Time has a corresponding torque value. When the torque sensed by the first controller 724 of the control device 70 at any sampling time is greater than the corresponding torque value of the predetermined torque, the second drive signal output by the first controller 724 of the control device 70 includes A current drop signal, so that the driving device 60 reduces the running current of the motor 20, so that the torque decreases correspondingly. The first controller 724 of the control device 70 at any one of the sampling time, when the sensed torque is less than the torque value corresponding to the predetermined torque, the second drive signal output by the first controller 724 of the control device 70 includes A current signal is used to make the driving device 60 increase the operating current of the motor to increase the torque. In this way, the change of the torque sensed by the torque sensing module 50 within the first predetermined period can conform to the change relationship of the predetermined torque with respect to time.

By pre-determining the change relationship of torque with respect to time, and cooperating with the torque sensed by the torque sensing module 50, the torque drop can be controlled more accurately, avoiding too fast or too slow drop of torque, so that the drop of torque can be controlled more accurately .

In the above-mentioned embodiments, it is taken that the driving device 60 has the controller 68 as an example, and the control device 70 has the first and second controllers 724 and 744 as an example. In one embodiment, the functions of the controller 68 of the driving device 60 can also be incorporated into the first controller 724, that is, the first controller 724 is electrically connected to the Hall sensors 66 and outputs the driving signal. The switching elements 64 are commutated to drive the rotor of the motor 20 to rotate. In one embodiment, the first controller 724 and the second controller 744 can also be integrated on the same circuit board, or integrated into one controller.

According to the above, the electric tool and the control method thereof of the present invention can effectively reduce the user's discomfort when operating the electric tool to lock and disassemble the workpiece, and avoid injury to the user's wrist.

The above description is only a preferred feasible embodiment of the present invention, and all equivalent changes made by applying the description of the present invention and the scope of the patent application should be included in the scope of the patent of the present invention.

1: Power tools

10: shell

12:Handheld part

14: Transmission department

20: motor

22: Shaft

30:Deceleration mechanism

302: input terminal

304: output terminal

40: drive shaft

42: Tool head

50:Torque sensing module

60: drive device

70: Control device

72: First control device

74: Second control device

80: battery

82: Operation interface

822: start switch

824: Steering switch

826: Torque setter

D1: the first direction of rotation

D2: Second direction of rotation

Claims (18)

An electric tool, comprising: a motor with a rotating shaft; a reduction mechanism with an input end and an output end, the input end connected to the rotation shaft of the motor; a drive shaft connected to the output end of the reduction mechanism; a torque sensor A measuring module, which senses a torque on the driving shaft; a driving device, which is electrically connected to the motor and used to drive the motor; and a control device, which is electrically connected to the driving device and the torque sensing module group, the control device is operable in a first rotation mode, and in the first rotation mode, the control device outputs a first drive signal to the drive device, so that the drive device drives the motor to rotate so that the shaft rotates along the When a first rotation direction rotates and the control device judges that the torque sensed by the torque sensing module rises to a first predetermined torque, the control device outputs a second drive signal to the drive within a first predetermined period device, so that the driving device gradually reduces an operating current of the motor within the first predetermined period, and when the control device judges that the torque sensed by the torque sensing module drops to a second predetermined torque, it stops outputting the The second driving signal is sent to the driving device to make the driving device stop the motor; wherein, the first predetermined torque is a torque required for locking the workpiece. The electric tool as described in claim 1, wherein the control device outputs the second torque according to the comparison between a predetermined torque relative to time and the torque sensed by the torque sensing module within the first predetermined period. drive signal. The electric tool according to claim 2, wherein the control device obtains the sensed torque at every sampling time within the first predetermined period, and the change of the predetermined torque with respect to time is related to any one of the sampling times has a corresponding torque value; where the control When the torque sensed by the device at any sampling time is greater than the corresponding torque value of the predetermined torque, the second drive signal output by the control device includes a current reduction signal, so that the drive device reduces the operating current of the motor ; Wherein the control device is at any one of the sampling times when the sensed torque is less than the torque value corresponding to the predetermined torque, the second drive signal output by the control device includes a rising current signal, so that the drive device increases the The operating current of the motor. The electric tool as described in claim 1, comprising a current detection module electrically connected to the motor and the control device and detecting the operating current of the motor; the control device operates according to a predetermined The change relation of current relative to time is compared with the operating current to output the second driving signal. The electric tool as described in claim 4, wherein the control device acquires the detected operating current at intervals of a sampling time within the first predetermined period, and the change of the predetermined current relative to time is related to any one of the The sampling time has a corresponding current value; wherein when the operating current detected by the control device at any sampling time is greater than the current value corresponding to the predetermined current, the second drive signal output by the control device includes a drop current signal, so that the driving device reduces the running current of the motor; wherein the control device outputs the The second driving signal includes a current boost signal to make the driving device increase the running current of the motor. The electric tool according to claim 1, wherein the first predetermined period is longer than 100 milliseconds. The electric tool as described in claim 1, wherein the control device is operable in a second rotation mode, and in the second rotation mode, the control device outputs a third driving signal to the driving device, and the third driving The signal makes the drive device drive the drive device according to a first rotational speed The motor runs so that its shaft generates a rotational force along a second rotational direction, wherein the second rotational direction is opposite to the first rotational direction, and the control device judges that the torque sensed by the torque sensing module rises to a first When the predetermined torque then decreases, the control device outputs a fourth driving signal to the driving device within a second predetermined period, and the fourth driving signal makes the driving device drive the motor to rotate in a manner of gradually increasing the rotational speed to make its shaft Continue to generate the rotational force along the second rotational direction. The electric tool as described in claim 7, wherein the third driving signal is to make the driving device drive the motor to rotate according to the first rotational speed so that the rotating shaft generates a rotational force along the second rotational direction and gradually increases to a second The rotation speed drives the motor to run; wherein the fourth drive signal in the second predetermined period causes the driving device to gradually increase from the second rotation speed to a third rotation speed to drive the motor to run. The electric tool as claimed in claim 8, wherein the fourth driving signal in the second predetermined period causes the driving device to gradually increase from the second speed to the third speed to drive the motor with a positive slope. A method for controlling an electric tool, wherein the electric tool includes a motor with a rotating shaft; a reduction mechanism with an input end and an output end, the input end is connected to the rotation shaft of the motor; a drive shaft is connected to the reduction mechanism output end; a torque sensing module, which senses a torque on the drive shaft; a driving device, electrically connected to the motor and used to drive the motor; a control device, electrically connected to the torque sensor The module and the drive device; the control method is executed by the control device, including the following steps: A. Operate in a first rotation mode; output a first drive signal to the drive device to make the drive device drive the motor Run to make the rotating shaft rotate along a first rotation direction; B. When judging that the torque sensed by the torque sensing module rises to a first predetermined torque, output a second drive signal to the drive within a first predetermined period device, so that the driver Set to gradually reduce an operating current of the motor within the first predetermined period; wherein, the first predetermined torque is a torque required to lock the workpiece; C. Judging that the torque sensed by the torque sensing module drops to a When the second predetermined torque is reached, stop outputting the second driving signal to the driving device, so that the driving device stops the motor from running. The control method of an electric tool as described in claim 10, wherein in the control method in step B, within the first predetermined period, a change relationship of a predetermined torque relative to time and the torque sensed by the torque sensing module are used. Output the second driving signal according to torque comparison. The control method of the electric tool according to claim 11, wherein, in step B, the sensed torque is obtained every sampling time within the first predetermined period, and the change of the predetermined torque relative to time There is a torque value corresponding to any of the sampling times; wherein when the torque sensed at any of the sampling times is greater than the torque value corresponding to the predetermined torque, the output second drive signal includes a current-down signal, In order to make the driving device reduce the operating current of the motor; wherein at any one of the sampling times, when the sensed torque is smaller than the corresponding torque value of the predetermined torque, the output second driving signal includes a rising current signal, To make the driving device increase the operating current of the motor. The control method of the electric tool as described in claim 10, wherein the electric tool includes a current detection module, electrically connected to the motor and detecting the operating current of the motor; the control method is in step B, in the second The second driving signal is outputted according to a predetermined current variation relationship with time and compared with the operating current within a predetermined period. The control method of the electric tool according to claim 13, wherein in step B, the operation current is detected every sampling time within the first predetermined period, and the change of the predetermined current relative to time is related to any A current value corresponding to the sampling time; wherein the operating current detected at any sampling time is greater than the corresponding predetermined current When the current value is high, the outputted second drive signal includes a current drop signal, so that the drive device reduces the operating current of the motor; wherein at any one of the sampling times, the detected operating current is less than the corresponding predetermined current When the current value is higher, the output second drive signal includes a current boost signal to make the drive device increase the operating current of the motor. The control method of an electric tool according to claim 10, wherein the first predetermined period is longer than 100 milliseconds. The control method of the electric tool as described in claim 10, comprising: D. operating in a second rotation mode; outputting a third driving signal to the driving device, and the third driving signal makes the driving device drive according to a first rotational speed The motor operates to make the rotating shaft generate a rotational force along a second rotational direction, wherein the second rotational direction is opposite to the first rotational direction; E, judging that the torque sensed by the torque sensing module rises to a third When the predetermined torque then drops, a fourth drive signal is output to the drive device within a second predetermined period, and the fourth drive signal makes the drive device drive the motor in a manner of gradually increasing the rotational speed so that the shaft continues to generate The rotational force of the second rotational direction. The control method of the electric tool according to claim 16, wherein in step D, the third driving signal is to instruct the driving device to drive the motor to rotate according to the first rotational speed so that the rotating shaft generates a rotational force along the second rotational direction and Gradually increasing to a second rotational speed to drive the motor to run; wherein in step E, the fourth driving signal within the second predetermined period is to make the drive device gradually increase from the second rotational speed to a third rotational speed to drive the motor to run. The control method of the electric tool as described in claim 17, wherein in step E, the fourth driving signal within the second predetermined period is to make the driving device gradually increase from the second speed to the third speed with a positive slope to drive The motor runs.

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