Power tool and control method thereof

Abstract

A power tool includes a motor, a drive shaft, a torque sensing module and a control device. The control method includes: the control device drives the motor to rotate the rotation shaft in a rotation direction; the control device determines that the torque sensed by the torque sensing module rises, and drives the motor in a plurality of first start-stop cycles; the control device determines that the torque sensed by the torque sensing module rises to a first predetermined torque and is less than a second predetermined torque, and drives the motor in a plurality of second start-stop cycles. In this way, during the locking or disassembling of the workpiece, when the torque rises, the discomfort of the user's hand caused by the reaction force can be effectively reduced.

Description

Technical Field

[0001] This invention relates to power tools; in particular, it refers to a power tool without a clutch mechanism and a control method thereof. Background Technology

[0002] Traditional power tools, such as electric torque screwdrivers or electric torque wrenches without a clutch mechanism, allow users to set a torque and tighten screws, nuts, and other workpieces according to that setting. When the tightening torque reaches the user-set torque, the power tool's motor immediately stops rotating. This ensures the workpiece is tightened to the user-defined torque.

[0003] However, during the process of locking the workpiece, the user's hand must exert force to resist the rotational force generated by the power tool in order to maintain stability. However, the higher the torque of locking the workpiece, the greater the reaction force on the user's hand, causing discomfort to the user's hand, especially wrist discomfort.

[0004] The same situation occurs when disassembling a locked workpiece. The tighter the workpiece is locked, the higher the torque required to rotate it, and the user's hand will also experience high reaction force, leading to discomfort.

[0005] Therefore, the design of traditional power tools is still imperfect and there are still areas for improvement. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a power tool and a control method thereof, which can reduce the discomfort experienced by the user when using the power tool to lock or disassemble a workpiece.

[0007] To achieve the above objectives, the present invention provides an electric tool comprising a motor, a drive shaft, a torque sensing module, and a control device. The motor has a rotating shaft; the drive shaft is coupled to the rotating shaft; the torque sensing module senses a torque applied to the drive shaft; the control device is electrically connected to the motor and the torque sensing module. The control device drives the motor to rotate its rotating shaft in a rotation direction, and when the control device determines that the torque sensed by the torque sensing module increases, it drives the motor in a plurality of first start-stop cycles. Each first start-stop cycle has a first period of time, the first period of time including a first start time and a first stop time. The control device drives the motor's rotating shaft to rotate during the first start time and during the first stop time. The control device stops the rotation of the motor shaft intermittently. The first cycle time of the plurality of first start-stop cycles gradually increases, and the plurality of first start times gradually increase. Then, when the control device determines that the torque sensed by the torque sensing module rises to a first predetermined torque and is less than a second predetermined torque, the control device drives the motor with a plurality of second start-stop cycles. Each second start-stop cycle has a second cycle time, which includes a second start time and a second stop time. The control device drives the rotation of the motor shaft at the second start time and stops the rotation of the motor shaft at the second stop time. The second cycle time of the plurality of second start-stop cycles remains fixed, and the plurality of second start times gradually increase, while the plurality of second stop times gradually decrease.

[0008] The present invention further provides a control method for an electric tool, the electric tool comprising a motor, a drive shaft, a torque sensing module, and a control device, wherein the motor has a rotating shaft; the drive shaft is coupled to the rotating shaft; the torque sensing module senses a torque applied to the drive shaft; the control device is electrically connected to the motor and the torque sensing module; the control method comprises the following steps:

[0009] A. The control device drives the motor to rotate its shaft in a rotation direction;

[0010] B. When the control device determines that the torque sensed by the torque sensing module increases, it drives the motor with multiple first start-stop cycles, wherein each first start-stop cycle has a first cycle time, the first cycle time including a first start time and a first stop time; the control device drives the motor shaft to rotate at the first start time and stops the motor shaft rotation at the first stop time; wherein the first cycle time of the multiple first start-stop cycles gradually increases and the multiple first start times gradually increase; and

[0011] C. When the control device determines that the torque sensed by the torque sensing module rises to a first predetermined torque but is less than a second predetermined torque, it drives the motor with multiple second start-stop cycles. Each second start-stop cycle has a second cycle time, which includes a second start time and a second stop time. The control device drives the motor shaft to rotate at the second start time and stops the motor shaft from rotating at the second stop time. The second cycle time of the multiple second start-stop cycles is kept fixed, and the multiple second start times gradually increase while the multiple second stop times gradually decrease.

[0012] Therefore, when encountering increased torque during the locking or disassembly of workpieces, the aforementioned power tools and their control methods can effectively reduce the discomfort caused to the user's hands by the reaction force. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a power tool according to a first preferred embodiment of the present invention.

[0014] Figure 2 This is a system block diagram of a power tool according to a first preferred embodiment of the present invention.

[0015] Figure 3 This is a flowchart of the first rotation mode of the power tool control method according to the first preferred embodiment of the present invention.

[0016] Figure 4 The curves of torque, cycle time, start time, and stop time sensed by the torque sensing module when locking the workpiece according to the first preferred embodiment of the present invention are shown.

[0017] Figure 5 This is a schematic diagram of multiple first start-stop cycles according to a first preferred embodiment of the present invention.

[0018] Figure 6 This is a schematic diagram of multiple second start-stop cycles according to a first preferred embodiment of the present invention.

[0019] Figure 7 This is a flowchart of the second rotation mode of the power tool control method according to the first preferred embodiment of the present invention.

[0020] Figure 8 The curves of torque, cycle time, start time, and stop time sensed by the torque sensing module during workpiece disassembly in the first preferred embodiment of the present invention are shown. Detailed Implementation

[0021] To more clearly illustrate the present invention, preferred embodiments are described in detail below with reference to the accompanying drawings. Please refer to...Figure 1 and Figure 2 The power tool shown is a first preferred embodiment of the present invention, comprising a housing 10, a motor 12, a drive shaft 14, a torque sensing module 16, and a control device 18. The power tool does not have a clutch mechanism.

[0022] In this embodiment, the housing 10 has a handheld portion 102 and a transmission portion 104. The handheld portion 102 is attached to the lower part of the transmission portion 104, and the long axis of the handheld portion 102 intersects with that of the transmission portion 104. However, this does not mean that the long axis of the handheld portion 102 and the transmission portion 104 may be on the same axis. The handheld portion 102 is for the user to hold and has a battery 24 at its bottom.

[0023] The motor 12 is disposed on the transmission part 104 and has a rotating shaft 122. In this embodiment, the motor 12 is a three-phase DC brushless motor.

[0024] The drive shaft 14 is coupled to the rotating shaft 122 of the motor 12. In this embodiment, the drive shaft 14 is coupled to the rotating shaft 122 of the motor 12 via a reduction mechanism 26. The reduction mechanism 26 may be, for example, a planetary gear reducer. The drive shaft 14 may be fitted with a tool head 28 for rotating a workpiece, such as a screw or nut. For example, the tool head may be, for example, an external hexagonal, internal hexagonal, Phillips, or slotted head tool head for driving internal hexagonal, external hexagonal, Phillips, or slotted screws.

[0025] The torque sensing module 16 is coupled to the drive shaft 14 and is used to sense the torque on the drive shaft 14. In this embodiment, the torque sensing module 16 is set on the drive shaft 14 as an example, but it is not limited thereto. It can also be set at any position that can sense the torque on the drive shaft 14, and indirectly sense the torque on the drive shaft 14. For example, it can be set on the reduction mechanism 26 and coupled to the drive shaft 14 through the reduction mechanism 26.

[0026] The control device 18 is electrically connected to the motor 12 and the torque sensing module 16, and drives the rotating shaft 122 of the motor 12 to rotate. In this embodiment, the control device 18 drives the motor 12 through a drive module 30. The drive module 30 has multiple commutation switching elements 302 and a gate driver 304. The multiple commutation switching elements 302 are electrically connected to the motor 12. The control device 18 is electrically connected to the motor 12 through the drive module 30, and controls the gate driver 304 of the drive module 30 to switch the commutation switching elements 302, thereby driving the rotating shaft 122 of the motor 12 to rotate.

[0027] The control device 18, for example, has two control circuit boards: a first control circuit board 20 and a second control circuit board 22. The first control circuit board 20 has a first controller 202, and the second control circuit board 22 has a second controller 222. The first controller and the second controller can be, for example, microprocessors. In practice, the two control circuit boards can also be integrated into one, and the two controllers can be integrated into one controller.

[0028] The first control circuit board 20 is electrically connected to the torque sensing module 16 and the drive module 30. The second control circuit board 22 is electrically connected to the first control circuit board 20 and an operating interface 32 to receive power from the first control circuit board 20 and to transmit an operating command from the second controller 222 to the first controller 202.

[0029] The operating interface 32 includes a start switch 322, a direction switching switch 324, and a torque setter 326. The start switch 322 is operated by the user to output a start signal to the second controller 222. The direction switching switch 324 is operated by the user to switch between forward and reverse states, thereby outputting a direction signal to the second controller 222. The direction signal is either a forward or reverse signal. The torque setter 326 allows the user to set a target torque required to lock the workpiece. The second controller 222 transmits the set target torque to the first controller 202. The second controller 222 generates an operation command corresponding to the forward or reverse signal based on the start signal and the direction signal and transmits it to the first controller 202.

[0030] The control device 18 operates in a first rotation mode or a second rotation mode according to the operation command. In this embodiment, when the operation command received by the first controller 202 corresponds to the forward rotation signal, the first controller 202 operates in the first rotation mode; when the operation command received by the first controller 202 corresponds to the reverse rotation signal, the first controller 202 operates in the second rotation mode. The first rotation mode is used to control the drive module 30 to drive the shaft 122 of the motor 12 to rotate along a first rotation direction D1 for locking the workpiece; the second rotation mode is used to control the drive module 30 to drive the shaft 122 of the motor 12 to rotate along a second rotation direction D2 for disassembling the workpiece.

[0031] The user sets the target torque through the torque setter 326, switches the steering switch 324 to the forward rotation state, and presses the start switch 322 to start the first operation mode to lock the workpiece.

[0032] The steps of the control method in the first operating mode of this embodiment will be described below, including: Figure 3 The following steps are shown.

[0033] Step S11: The control device 18 drives the motor 12 to rotate its shaft along a rotation direction (first rotation direction D1). In this embodiment, the first controller 202 controls the drive module 30 to drive the motor 12 to rotate its shaft 122 along the first rotation direction D1. The shaft 122 drives the drive shaft 14 to rotate through the reduction mechanism 26, thereby rotating the workpiece.

[0034] Please refer to Figure 4 The first controller 202 controls the drive module 30 to drive the motor 12 for a fixed initial cycle time T0, and controls the drive module 30 to drive the motor 12's shaft 122 to rotate at a fixed speed. At the beginning of rotation, the torque sensed by the torque sensing module 16 is an initial torque, assuming 0 Nm. The initial cycle time T0 has an initial start time T0on and an initial stop time T0off. The control device 18 drives the motor shaft to rotate at the initial start time T0on and stops the motor 12 from rotating at the initial stop time T0off. In this embodiment, the initial cycle time T0 can be between 25 and 40 ms, the initial start time T0on can be between 5 and 15 ms, and the initial stop time T0off can be between 20 and 25 ms. For example, the initial cycle time T0 is 33 ms, the initial start time T0on is 10 ms, and the initial stop time T0off is 23 ms.

[0035] Step S12: When the control device 18 determines that the torque sensed by the torque sensing module 16 increases, it drives the motor 12 in multiple first start-stop cycles.

[0036] As the resistance encountered by the workpiece gradually increases, torque is generated on the drive shaft 14, and therefore, the torque sensed by the torque sensing module 16 increases. Please cooperate. Figure 4 and Figure 5When the first controller 202 determines that the torque sensed by the torque sensing module 16 has increased, it controls the drive module 30 to drive the motor 12 in a continuous first start-stop cycle. Each first start-stop cycle has a first cycle time T1, which includes a first start time T1on and a first stop time T1off. In each first start-stop cycle, the control device 18 drives the motor shaft to rotate at the first start time T1on and stops the rotation of the motor shaft at the first stop time T1off. Each first cycle time T1 gradually increases from the initial cycle time T0.

[0037] The first cycle time T1 of the plurality of first start-stop cycles gradually increases, and the plurality of first start times T1on gradually increases. In this embodiment, the plurality of first stop times T1off of the plurality of first start-stop cycles gradually increases, starting from the initial stop time T0off. Preferably, each first start-stop cycle has a first duty cycle, and the first duty cycles of the plurality of first start-stop cycles are the same, with each first duty cycle ranging from 25% to 35%. In this embodiment, the first duty cycle is 30%. The first cycle time T1 and the first start time T1on of the plurality of first start-stop cycles gradually increase as the torque sensed by the torque sensing module 16 increases, so as to achieve the purpose of the motor output following the increase of torque. However, this is not a limitation. In other embodiments, the first cycle time T1 and the first start time T1on of the plurality of first start-stop cycles may also increase with time.

[0038] More specifically, the first controller 202 of the control device 18 establishes a correspondence (i.e., a first correspondence) related to the torque sensed by the torque sensing module 16 and the changes in the plurality of first cycle times T1. The first correspondence may be, for example, a lookup table recording different torques and different first cycle times T1, or a formula relating torque and first cycle time T1. The control device 18 obtains the first cycle time T1 of each first start-stop cycle based on the torque sensed by the torque sensing module and the first correspondence, for example, by looking up the corresponding first cycle time T1 through a lookup table or by calculating the formula. Then, each first cycle time T1 is subtracted from each first stop time T1off to obtain the first start time T1on of each first start-stop cycle, preferably maintaining the same first duty cycle. For example, the control device 18 can obtain a first cycle time T1 and a corresponding first start time T1on according to the first correspondence at every sampling time, and drive the rotating shaft 122 of the motor 12 to rotate at the first start time T1on, and stop the rotation of the motor shaft at the first stop time T1off after the first start time T1on ends.

[0039] In practice, the first correspondence can also be related to the change in torque sensed by the torque sensing module 16 and the plurality of first start times. The first correspondence can be, for example, a lookup table recording different torques and different first start times T1on, or a formula relating torque and first start time T1on. The control device 18 obtains each first start time based on the torque sensed by the torque sensing module 16 and the first correspondence. For example, the control device 18 can obtain a first start time T1on at each sampling time using the first correspondence, drive the motor shaft to rotate at the first start time T1on, and stop the rotation of the motor shaft at a first stop time T1off after the first start time T1on ends.

[0040] The first cycle time T1 of the multiple first start-stop cycles gradually increases, so that the force transmitted by the motor 12 to the workpiece via the drive shaft 14 will generate vibration, and the frequency of vibration will gradually decrease as the sensed torque increases. In conjunction with the gradual increase of the multiple first start times T1on, that is, the output of the motor 12 gradually increases, thereby acting like intermittently tapping the workpiece, with the tapping speed gradually slowing down and the tapping force gradually increasing, so as to continuously lock the workpiece to the first predetermined torque, which can effectively reduce the discomfort caused to the user's hand by the reaction force.

[0041] In this embodiment, when the control device 18 determines that the torque sensed by the torque sensing module 16 has not yet reached the first predetermined torque and the first cycle time T1 of any first start-stop cycle has increased to an upper limit cycle time, the control device 18 maintains the first cycle time T1 of subsequent first start-stop cycles at the upper limit cycle time and the subsequent first start time T1on no longer increases. This avoids discomfort caused by excessively slow tapping speed. In this embodiment, the upper limit cycle time can be between 60 and 70 ms. For example, if the upper limit cycle time is 66 ms, then the first start time T1on is 19.8 ms and the first stop time T1off is 46.2 ms.

[0042] Step S13: When the control device 18 determines that the torque sensed by the torque sensing module 16 has risen to a first predetermined torque and is less than a second predetermined torque, it drives the motor 12 in multiple second start-stop cycles.

[0043] Please cooperate. Figure 4 and Figure 6 When the first controller 202 determines that the torque sensed by the torque sensing module 16 has risen to the first predetermined torque, it switches to controlling the drive module 30 to drive the motor in a continuous second start-stop cycle. Each second start-stop cycle has a second cycle time T2, which includes a second start time T2on and a second stop time T2off. The second cycle time T2 is equal to the upper limit cycle time. In this embodiment, the second cycle time T2 can be between 60 and 70 ms. For example, the second cycle time T2 is 66 ms. In each second start-stop cycle, the control device 18 drives the motor 12 to rotate at the second start time T2on and stops the motor 12 from rotating at the second stop time T2off. The second cycle time T2 of the plurality of second start-stop cycles remains fixed, and the plurality of second start times T2on gradually increases, while the plurality of second stop times T2off gradually decreases. That is, the plurality of second duty cycles gradually increase, starting from the first duty cycle. The plurality of second start times T2on gradually increase as the torque sensed by the torque sensing module 16 increases, and the plurality of second stop times T2off gradually decrease as the torque sensed by the torque sensing module 16 increases, so as to achieve the purpose of the motor 12's duty cycle following the increase of torque. However, this is not a limitation. In other embodiments, the plurality of second start times T2on may also gradually increase with time, and the plurality of second stop times T2off may also gradually decrease with time.

[0044] In this embodiment, the second cycle time T2 is equal to the first cycle time T1 of the last first start-stop cycle or equal to the upper limit cycle time. The second predetermined torque is set to be equal to the target torque set by the user, but is not limited to this; the second predetermined torque may also be less than the target torque. The increase in the torque sensed by the torque sensing module 16 with the plurality of second start times T2on is greater than the increase in the torque sensed by the torque sensing module 16 with the plurality of first start times T1on. The change in the plurality of second start times T2on is the same as the change in the plurality of second stop times T2off, thereby keeping the second cycle time T2 of the plurality of second start-stop cycles fixed.

[0045] More specifically, the first controller 202 of the control device 18 establishes a correspondence (i.e., a second correspondence), which relates to the torque sensed by the torque sensing module 16 and the changes in the plurality of second start times. The second correspondence can be, for example, a lookup table recording different torques and different second start times, or a formula relating torque and second start times. The first controller 202 of the control device 18 obtains the second start time T2on of each second start-stop cycle based on the torque sensed by the torque sensing module 16 and the second correspondence, for example, by looking up the corresponding second start time T2on through a lookup table or by calculating the formula. Then, the second start time T2on is subtracted from the second cycle time T2 to obtain the second stop time T2off of each second start-stop cycle. Preferably, the second duty cycle of the plurality of second start-stop cycles gradually increases. For example, the control device 18 can obtain a second start time T2on and a corresponding second stop time T2off according to the second correspondence at every sampling time, and drive the motor shaft 122 to rotate at the second start time T2on, and stop the rotation of the motor shaft at the second stop time T2off after the second start time T2on ends.

[0046] In practice, the second correspondence can also be related to the torque sensed by the torque sensing module 16 and the change of the plurality of second stop times T2off. The first controller 202 of the control device 18 obtains the second stop time T2off of each second start-stop cycle according to the torque sensed by the torque sensing module 16 and the second correspondence, and then subtracts each second stop time T2off from the second cycle time T2 to obtain the second start time T2on of each second start-stop cycle.

[0047] Since the second cycle time T2 of the multiple second start-stop cycles remains fixed, the force transmitted from the motor 12 to the workpiece via the drive shaft 14 will generate vibration, and the vibration frequency is fixed. With the multiple second start times T2on gradually increasing, that is, the output of the motor 12 gradually increases. In this way, it is like intermittently striking the workpiece at a fixed frequency, and the striking force gradually increases, so as to continuously lock the workpiece to a second predetermined torque with higher torque. This can effectively reduce the discomfort caused by the reaction force to the user's hand during the high torque stage.

[0048] In this embodiment, when the second start time T2on of any second start-stop cycle reaches an upper limit start time, or the second stop time T2off of any second start-stop cycle reaches a lower limit stop time, the control device 18 maintains the second start time T2on of the subsequent second start-stop cycle at the upper limit start time, and the subsequent second stop time T2off is maintained at the lower limit stop time. The upper limit start time can be less than the second cycle time T2, for example, the upper limit start time is 45-55% of the second cycle time T2, that is, the second duty cycle is at most 45-55%, preferably 50%, to maintain the effect of knocking.

[0049] As described above, during the process from the generation of torque on the drive shaft 14 to the locking of the workpiece, since the initial torque on the drive shaft 14 is not large, maintaining a fixed first duty cycle (25-35%) for all the multiple first start-stop cycles can prevent the workpiece from directly driving the motor 12 with a large duty cycle in the initial locking stage, thus avoiding large vibrations in the power tool. Afterwards, once the torque on the drive shaft 14 increases to a first predetermined torque, the multiple second start-stop cycles gradually increase the duty cycle, allowing the output of the motor 12 to gradually increase, achieving the purpose of continuously locking the workpiece.

[0050] This embodiment may also include step S14. Step S14: When the control device 18 determines that the torque sensed by the torque sensing module 16 has reached the target torque, it stops the motor 12 from rotating.

[0051] In this embodiment, when the torque for locking the workpiece reaches the target torque, the first controller 202 of the control device 18 stops the motor 12 from rotating, thereby locking the workpiece to the target torque. Since the first controller 202 in this embodiment sets the second predetermined torque to be equal to the target torque, the first controller 202 stops the motor 12 from rotating when it determines that the torque sensed by the torque sensing module has risen to the second predetermined torque.

[0052] When the user wants to disassemble the workpiece, he / she switches the direction switching switch 324 to the reverse state and presses the start switch 322 to start the second operation mode to disassemble the workpiece.

[0053] The steps of the control method in the second operating mode of this embodiment will be described below, including: Figure 7 The following steps are shown.

[0054] Step S21: The control device 18 drives the motor 12 to rotate its shaft along a rotation direction (second rotation direction D2). In this embodiment, the first controller 202 controls the drive module 30 to drive the motor 12 to rotate its shaft along the second rotation direction D2. Please refer to... Figure 8 At the beginning of rotation, the torque sensed by the torque sensing module 16 is an initial torque, which is 0 Nm for example.

[0055] Step S22: When the control device 18 determines that the torque sensed by the torque sensing module 16 has increased, it drives the motor 12 using the plurality of first start-stop cycles. In this embodiment, step S22 is the same as step S12.

[0056] Step S23: When the control device 18 determines that the torque sensed by the torque sensing module 16 has risen to the first predetermined torque but is less than the second predetermined torque, it drives the motor 12 using the plurality of second start-stop cycles. In this embodiment, step S23 is largely the same as step S13, except that the second predetermined torque in step S23 is a preset torque, rather than a target torque set by the user.

[0057] During the disassembly of the workpiece, in step S22, the first cycle time T1 of the plurality of first start-stop cycles gradually increases. As a result, the force transmitted by the motor 12 to the workpiece via the drive shaft 14 will generate vibration, and the frequency of vibration will gradually decrease as the sensed torque increases. In conjunction with the gradual increase of the plurality of first start times T1on, that is, the output of the motor 12 gradually increases. This is like intermittently tapping the workpiece, with the tapping speed gradually slowing down and the tapping force gradually increasing, in order to try to loosen the workpiece gradually. This can effectively reduce the discomfort caused to the user's hands by the reaction force. In step S23, the second cycle time T2 of the plurality of second start-stop cycles remains fixed. In this way, the force transmitted by the motor 12 to the workpiece via the drive shaft 14 will generate vibration, and the vibration frequency is fixed. With the plurality of second start times gradually increasing, that is, the output of the motor gradually increases, thereby acting as if the workpiece is being tapped intermittently at a fixed frequency, and the force of the tapping gradually increases, in order to try to loosen the workpiece continuously. This can effectively reduce the discomfort caused to the user's hand by the reaction force during the high torque stage.

[0058] This embodiment may also include step S24. Step S24: When the control device 18 determines that the torque sensed by the torque sensing module has risen to the second predetermined torque, it drives the motor 12 in multiple third start-stop cycles until it determines that the torque sensed by the torque sensing module 16 has decreased, and then drives the motor 12 to increase the rotation speed of its shaft along the second rotation direction D2.

[0059] The third start-stop cycle drive has a third cycle time T3, which includes a third start time T3on and a third stop time T3off. The third cycle time T3 is maintained equal to the second cycle time T2, the third start time T3on is maintained equal to the second start time T2on of the last second start-stop cycle, and the third stop time T3off is maintained equal to the second stop time T2off of the last second start-stop cycle. The third responsibility cycle of the plurality of third start-stop cycles is maintained equal to the maximum value of the second responsibility cycles of the plurality of second start-stop cycles.

[0060] When the torque sensed by the torque sensing module 16 decreases, it indicates that the workpiece has loosened from its locked state. At this time, the first controller 202 controls the drive module 30 to change the cycle time of the drive motor 12 from the third cycle time T3 to a fourth cycle time T4, and controls the motor 12 to increase its speed to accelerate the workpiece rotation. Taking 100% as an example, the fourth duty cycle of the fourth cycle time T4 is equal to the fourth cycle time T4. The fourth cycle time T4 can be less than the third cycle time T3, but this is not a limitation; it can also be equal to the third cycle time T3. When the second controller 222 detects that the user has released the start switch 322, it notifies the first controller 202 to stop the motor 12 from rotating.

[0061] As described above, the power tools and control methods of the present invention can effectively reduce the discomfort caused by the reaction force on the user's hands during the high torque stage, whether in the process of locking or disassembling a workpiece.

[0062] The above description is only a preferred and feasible embodiment of the present invention. Any equivalent changes made by applying the present invention specification and the claims should be included within the scope of the present invention.

[0063] Explanation of reference numerals in the attached figures

[0064] 10: Shell

[0065] 102: Handheld part

[0066] 104: Transmission Unit

[0067] 12: Motor

[0068] 122: Shaft

[0069] 14: Drive shaft

[0070] 16: Torque sensing module

[0071] 18: Control device

[0072] 20: First control circuit board

[0073] 202: First Controller

[0074] 22: Second control circuit board

[0075] 222: Second controller

[0076] 24: Battery

[0077] 26: Speed ​​reduction mechanism

[0078] 28: Tool head

[0079] 30: Driver Module

[0080] 302: Commutation switch element

[0081] 304: Gate Driver

[0082] 32: Operation Interface

[0083] 322: Start switch

[0084] 324: Steering switch

[0085] 326: Torque Setter

[0086] D1: First rotation direction

[0087] D2: Second rotation direction

[0088] T0: Initial cycle time

[0089] T0on: Initial startup time

[0090] T0off: Initial stopping time

[0091] T1: First cycle time

[0092] T1on: First Startup Time

[0093] T1off: First Stop Time

[0094] T2: Second cycle time

[0095] T2on: Second Startup Time

[0096] T2off: Second Stop Time

[0097] T3: Third cycle time

[0098] T3on: Third Startup Time

[0099] T3off: Third Stop Time

[0100] T4: Fourth cycle time

[0101] T4on: Fourth Startup Time

[0102] S11~S13: Steps

[0103] S21~S23: Steps

Claims

1. An electric tool, comprising: A motor, having a rotating shaft; A drive shaft is coupled to the rotating shaft; A torque sensing module senses a torque applied to the drive shaft; and A control device electrically connected to the motor and the torque sensing module; in, The control device drives the motor to rotate its shaft in a rotation direction. When the control device determines that the torque sensed by the torque sensing module increases, it drives the motor in multiple first start-stop cycles. Each first start-stop cycle has a first cycle time, which includes a first start time and a first stop time. The control device drives the motor shaft to rotate at the first start time and stops the motor shaft rotation at the first stop time. The first cycle time of the multiple first start-stop cycles gradually increases, and the multiple first start times also gradually increase. Subsequently, when the control device... When the torque sensed by the torque sensing module rises to a first predetermined torque but is less than a second predetermined torque, the control device drives the motor in multiple second start-stop cycles. Each second start-stop cycle has a second cycle time, which includes a second start time and a second stop time. The control device drives the motor shaft to rotate at the second start time and stops the motor shaft from rotating at the second stop time. The second cycle time of the multiple second start-stop cycles is kept fixed, and the multiple second start times gradually increase while the multiple second stop times gradually decrease.

2. The power tool as claimed in claim 1, wherein, The first cycle time and first start time of the plurality of first start-stop cycles gradually increase as the torque sensed by the torque sensing module increases; wherein, the plurality of second start times gradually increase as the torque sensed by the torque sensing module increases, and the plurality of second stop times gradually decrease as the torque sensed by the torque sensing module increases.

3. The power tool as claimed in claim 2, wherein, The extent to which the plurality of second start-up times increase with the torque sensed by the torque sensing module is greater than the extent to which the plurality of first start-up times increase with the torque sensed by the torque sensing module.

4. The power tool as claimed in claim 1, wherein, Each of the first start-stop cycles has a first responsibility period, and the first responsibility periods of the plurality of first start-stop cycles are the same; wherein each of the second start-stop cycles has a second responsibility period, and the second responsibility periods of the plurality of second start-stop cycles gradually increase.

5. The power tool as claimed in claim 1, wherein, The multiple first stop times of the multiple first start-stop cycles gradually increase.

6. The power tool as claimed in claim 5, wherein, When the control device determines that the torque sensed by the torque sensing module has not yet reached the first predetermined torque and the first cycle time of any first start-stop cycle has increased to an upper limit cycle time, the control device maintains the first cycle time of the subsequent first start-stop cycle at the upper limit cycle time and the subsequent first start time no longer increases.

7. The power tool as claimed in claim 5, wherein, The control device establishes a first correspondence relationship, which is related to the torque sensed by the torque sensing module and the change of the plurality of first cycle times; wherein, the control device obtains the first cycle time of each first start-stop cycle based on the torque sensed by the torque sensing module and the first correspondence relationship, and subtracts each first stop time from the obtained first cycle time to obtain the first start time of each first start-stop cycle.

8. The power tool as claimed in claim 5, wherein, The control device establishes a first correspondence relationship, which is related to the change between the torque sensed by the torque sensing module and the plurality of first start times; wherein, the control device obtains the first start time of each first start-stop cycle based on the torque sensed by the torque sensing module and the first correspondence relationship.

9. The power tool as claimed in claim 1, wherein, The control device establishes a second correspondence relationship, which is related to the change of the plurality of second start times of the torque sensed by the torque sensing module; wherein, the control device obtains the second start time of each second start-stop cycle based on the torque sensed by the torque sensing module and the second correspondence relationship, and subtracts the obtained second start time from each second cycle time to obtain the second stop time of each second start-stop cycle.

10. The power tool as claimed in claim 1, wherein, When the second start time of any second start-stop cycle reaches an upper limit start time, or the second stop time of any second start-stop cycle reaches a lower limit stop time, the control device maintains the second start time of the subsequent second start-stop cycle at the upper limit start time, or maintains the subsequent second stop time at the lower limit stop time.

11. The power tool as claimed in claim 1, wherein, When the control device determines that the torque sensed by the torque sensing module has reached a target torque, it stops the rotation of the motor shaft.

12. The power tool as claimed in claim 1, wherein, When the control device determines that the torque sensed by the torque sensing module rises to the second predetermined torque, it drives the motor in multiple third start-stop cycles until it determines that the torque sensed by the torque sensing module decreases, at which point it drives the motor to increase the rotational speed of its shaft along the rotation direction. Each third start-stop cycle has a third cycle time, which includes a third start time and a third stop time. The control device drives the motor shaft to rotate at the third start time and stops the rotation of the motor shaft at the third stop time. The third cycle time is equal to each of the second cycle times, the third start time is equal to the second start time of the last second start-stop cycle, and the third stop time is equal to the second stop time of the last second start-stop cycle.

13. A control method for an electric tool, wherein, The power tool includes a motor, a drive shaft, a torque sensing module, and a control device. The motor has a rotating shaft; the drive shaft is coupled to the rotating shaft; the torque sensing module senses a torque applied to the drive shaft; the control device is electrically connected to the motor and the torque sensing module; the control method includes the following steps: A. The control device drives the motor to rotate its shaft in a rotation direction; B. When the control device determines that the torque sensed by the torque sensing module increases, it drives the motor with multiple first start-stop cycles, wherein each first start-stop cycle has a first cycle time, the first cycle time including a first start time and a first stop time; the control device drives the motor shaft to rotate at the first start time and stops the motor shaft rotation at the first stop time; wherein the first cycle time of the multiple first start-stop cycles gradually increases and the multiple first start times gradually increase; and C. When the control device determines that the torque sensed by the torque sensing module rises to a first predetermined torque and is less than a second predetermined torque, it drives the motor with multiple second start-stop cycles, wherein each second start-stop cycle has a second cycle time, the second cycle time including a second start time and a second stop time; the control device drives the motor shaft to rotate at the second start time and stops the motor shaft from rotating at the second stop time; wherein the second cycle time of the multiple second start-stop cycles is kept fixed, the multiple second start times are gradually increased, and the multiple second stop times are gradually decreased.

14. The control method for power tools as described in claim 13, wherein, In step B, the first cycle time and the first start time of the plurality of first start-stop cycles gradually increase as the torque sensed by the torque sensing module increases; in step C, the plurality of second start times gradually increase as the torque sensed by the torque sensing module increases, and the plurality of second stop times gradually decrease as the torque sensed by the torque sensing module increases.

15. The control method for an electric tool as described in claim 14, wherein, The extent to which the plurality of second start-up times increase with the torque sensed by the torque sensing module is greater than the extent to which the plurality of first start-up times increase with the torque sensed by the torque sensing module.

16. The control method for an electric tool as described in claim 13, wherein, Each of the first start-stop cycles has a first responsibility period, and the first responsibility periods of the plurality of first start-stop cycles are the same; wherein each of the second start-stop cycles has a second responsibility period, and the second responsibility periods of the plurality of second start-stop cycles gradually increase.

17. The control method for an electric tool as described in claim 13, wherein, In step B, the multiple first stop times of the multiple first start-stop cycles remain fixed.

18. The control method for an electric tool as described in claim 17, wherein, In step B, when the control device determines that the torque sensed by the torque sensing module has not yet reached the first predetermined torque and the first cycle time of any first start-stop cycle has increased to an upper limit cycle time, the control device maintains the first cycle time of the subsequent first start-stop cycle at the upper limit cycle time and the subsequent first start time no longer increases.

19. The control method for an electric tool as described in claim 17, wherein, The control device establishes a first correspondence relationship, which is related to the torque sensed by the torque sensing module and the change of the plurality of first cycle times; wherein in step B, the control device obtains the first cycle time of each first start-stop cycle based on the torque sensed by the torque sensing module and the first correspondence relationship, and subtracts each first stop time from the obtained first cycle time to obtain the first start time of each first start-stop cycle.

20. The control method for an electric tool as described in claim 17, wherein, A first correspondence is established in the control device, which is related to the change between the torque sensed by the torque sensing module and the plurality of first start times; In step B, the control device obtains the first start time of each of the first start-stop cycles based on the torque sensed by the torque sensing module and the first correspondence.

21. The control method for an electric tool as described in claim 13, wherein, A second correspondence is established in the control device, which is related to the change of the plurality of second start times of the torque sensed by the torque sensing module; In step C, the control device obtains the second start time for each of the second start-stop cycles based on the torque sensed by the torque sensing module and the second correspondence, and subtracts the obtained second start time from each of the second cycle times to obtain the second stop time for each of the second start-stop cycles.

22. The control method for an electric tool as described in claim 13, wherein, In step C, when the second start time of any second start-stop cycle reaches an upper limit start time, or when the second stop time of any second start-stop cycle reaches a lower limit stop time, the control device maintains the second start time of the subsequent second start-stop cycle at the upper limit start time, or maintains the subsequent second stop time at the lower limit stop time.

23. The control method for power tools as described in claim 13, wherein, Step C is followed by determining when the torque sensed by the torque sensing module reaches a target torque, and then stopping the rotation of the motor shaft.

24. The control method for an electric tool as described in claim 13, wherein, Step C further includes determining that when the torque sensed by the torque sensing module rises to the second predetermined torque, driving the motor in multiple third start-stop cycles until it is determined that the torque sensed by the torque sensing module decreases, driving the motor to increase the rotational speed of its shaft along the rotation direction; wherein the third start-stop cycle has a third cycle time, the third cycle time has a third start time and a third stop time, the control device drives the motor shaft to rotate at the third start time, and stops the rotation of the motor shaft at the third stop time; wherein the third cycle time is equal to the second cycle time, the third start time is equal to the second start time of the last second start-stop cycle, and the third stop time is equal to the second stop time of the last second start-stop cycle.

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