Impact tool, electric tool and control method

Abstract

The invention discloses an impact tool, an electric tool and a control method, and the impact tool comprises a controller which is used for controlling a motor; wherein the controller comprises a first control mode; when entering the first control mode, the controller is configured to control the maximum output rotating speed of the motor to be a first rotating speed, limit the rotating speed of the motor to be a non-driving rotating speed in response to the running state of the motor reaching a first limiting condition, and drive the output shaft to output torque at a second rotating speed in response to the rotating speed of the motor being the non-driving rotating speed, the second rotating speed is smaller than the first rotating speed; the method is applicable to more working conditions.

Description

Technical Field

[0001] The present application relates to an electric tool, and in particular to an impact tool, an electric tool and a control method. Background Art

[0002] In the related art, during the operation process, the electric tool uses a motor to drive the output shaft to output torque outward, driving the fastener to rotate at high speed and screw into the target workpiece. When using an electric tool to drive the fastener into the workpiece, the user needs to skillfully control the electric tool so that the fastener can be flush with the workpiece, which places relatively high demands on the user's ability. In the related art, the electric tool identifies some of the working parameters of the electric tool to determine whether the fastener is working properly, and then shuts down the electric tool. However, due to the large variety of fasteners and target workpieces operated by the electric tool, it is difficult to accurately make the fastener flush with the workpiece.

[0003] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an impact tool that facilitates controlling the installation of a fastener flush with a workpiece.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions: An impact tool comprises: a motor, comprising a drive shaft rotating around a first axis; an output shaft driven by the motor, the output shaft being used to output torque to the outside; the output shaft rotates around the output axis; an impact mechanism being used to apply an impact force to the output shaft; the impact mechanism comprising: an impact block driven by the drive shaft and an anvil receiving impact from the impact block; the output shaft is formed or connected to the anvil; a controller being used to control the motor; wherein the controller comprises a first control mode; when entering the first control mode, the controller is configured to: control the maximum output speed of the motor to be a first speed, in response to the operating state of the motor reaching a first limiting condition, limit the speed of the motor to a non-driving speed, in response to the speed of the motor being the non-driving speed, the motor operates at a second speed to drive the output shaft to output torque, the second speed is less than the first speed, and the non-driving speed is less than the second speed.

[0006] In some embodiments, the running state of the motor reaches the first limiting condition including: after determining that the fastener operated by the output shaft is in the first set state according to the load parameter of the output shaft, the motor drives the output shaft to move to the position according to the preset condition.

[0007] In some embodiments, the motor drives the output shaft to move into position under preset conditions, including: the number of rotations of the motor drives the output shaft reaches a preset number of rotations, or the rotation time of the motor drives the output shaft reaches a preset time, or the axial displacement of the output shaft reaches at least one of a preset displacement amount.

[0008] In some embodiments, the load parameter of the output shaft includes at least one of a speed-related parameter of the motor and a current-related parameter of the motor.

[0009] In some embodiments, the load parameter of the output shaft includes at least one parameter of a rotational speed of the output shaft, a rotational angle of the output shaft, and a rotational acceleration of the output shaft.

[0010] In some embodiments, the number of revolutions of the motor-driven output shaft is represented by the commutation information of the motor.

[0011] In some embodiments, the commutation information of the motor includes: at least one of a commutation starting point, a commutation ending point, or a time required to complete each commutation.

[0012] In some embodiments, when the motor runs at a second speed, the motor receives a stop command, and the controller controls the motor to stop. When the motor receives a start signal again, it is determined that the difference between the time when the motor receives the start signal and the time when the motor receives the stop command is less than or equal to the first time parameter, and the impact tool enters the second control mode.

[0013] In some embodiments, in the second control mode, the controller limits the output of the motor, and the controller does not perform the control in the first control mode.

[0014] In some embodiments, the impact tool includes a power switch for receiving a user's power-on and power-off instructions. When the power switch is set to a preset state, the controller enters a first control mode.

[0015] In some embodiments, the power switch includes a travel switch, and when the displacement travel of the travel switch meets a preset travel, the controller enters the first control mode.

[0016] An impact tool comprises: a motor, comprising a drive shaft rotating around a first axis; an output shaft driven by the motor, the output shaft being used to output torque to the outside; the output shaft rotating around the output axis; an impact mechanism comprising: an impact block driven by the drive shaft and an anvil receiving impact from the impact block; the output shaft is formed or connected to the anvil; a controller for controlling the motor; wherein the controller comprises a first control mode; when entering the first control mode, the controller is configured such that: when the operating state of the motor reaches a first limiting condition, after limiting the output of the motor, the motor operates at a second speed and maintains the second speed to drive the output shaft to output torque, and the second speed is less than or equal to 50% of the maximum speed of the motor.

[0017] An electric tool comprises: a motor, an output shaft, driven by the motor, the output shaft is used to output torque to the outside; the output shaft rotates around the output axis; a controller is used to control the motor; wherein the controller comprises a first control mode; when entering the first control mode, the controller is configured to: control the maximum output speed of the motor to be a first speed, in response to the operating state of the motor reaching a first limiting condition, limit the speed of the motor to a non-driving speed, in response to the speed of the motor being the non-driving speed, drive the output shaft to output torque at a second speed, the second speed is less than the first speed, and the non-driving speed is less than the second speed.

[0018] A control method for an impact tool, the impact tool comprising: a motor, comprising a drive shaft rotating around a first axis; an output shaft driven by the motor, the output shaft being used to output torque to the outside; the output shaft rotating around the output axis; an impact mechanism comprising: an impact block driven by the drive shaft and an anvil receiving impact from the impact block; the output shaft being formed or connected to the anvil; a controller being used to control the motor; wherein the controller comprises a first control mode; when entering the first control mode, the control method comprises the following steps: controlling the maximum output speed of the motor to be a first speed; determining that the motor operating state reaches a first limiting condition; controlling the motor to limit output; the motor operating at a second speed and driving the output shaft to output torque, the second speed being less than the first speed.

[0019] A control method for an electric tool, the electric tool comprising: a motor, an output shaft, driven by the motor, the output shaft being used to output torque to the outside; the output shaft rotating around the output axis; a controller being used to control the motor; wherein the controller comprises a first control mode; when entering the first control mode, the control method comprises the following steps: controlling the maximum output speed of the motor to be a first speed; determining that the motor operating state reaches a first limiting condition; controlling the motor to limit output; the motor operating at a second speed and driving the output shaft to output torque, the second speed being less than the first speed.

[0020] The benefit of the present application is that when the running state of the motor reaches the first limiting condition, the motor is controlled to a non-driving speed, that is, the motor stops or is limited to near stop, and then automatically works at a low speed, which allows the user to accurately control the stop position of the screw and improve the success rate of the screw being flush with the target workpiece. Compared with the control logic of the related art that directly stops automatically after recognizing a certain state, the control scheme of the present application restarts at a low speed after stopping, which can be applied to more working conditions, has simpler recognition conditions, and high control robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application; Figure 2 yes Figure 1 Schematic diagram of a cross-sectional view of some components; Figure 3 is a circuit block diagram of an embodiment of the present application; Figure 4 is a schematic diagram of a process of fastening a gypsum board to a material plate (such as a metal plate) having a higher hardness than the gypsum board by using screws in the present application; Figure 5 is a schematic diagram of the process current (I) and the change with time (T) of fastening the gypsum board and the metal plate by screws in this application; Figure 6 is a control flow chart of the present application; Figure 7 is another control flow chart of the present application; Figure 8 This is the third control flow chart of this application. DETAILED DESCRIPTION

[0022] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0023] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0024] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0025] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0026] In this application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, etc. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0027] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0028] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0029] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are interchangeable. When a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0030] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0031] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0032] like Figure 1 and Figure 2 An impact tool of one embodiment of the present application is shown. The impact tool is an impact screwdriver 100. It can be understood that in other alternative embodiments, the impact tool can be equipped with different working accessories, and through these different working accessories, the impact tool can be, for example, an impact drill, an impact wrench, etc.

[0033] The impact screwdriver 100 includes a power supply. In the present embodiment, the power supply is a DC power supply 30. The DC power supply 30 is used to provide electrical energy to the impact screwdriver 100. The DC power supply 30 is a battery pack, and the battery pack cooperates with the corresponding power supply circuit to power the impact screwdriver 100. Those skilled in the art should understand that the power supply is not limited to the scenario of using a DC power supply, and can also be powered by AC power, AC power, and corresponding rectification, filtering and voltage regulation circuits to achieve power supply to the corresponding components in the machine. In the present embodiment, the DC power supply is a battery pack, and the battery pack 30 will be used to replace the DC power supply below, but it cannot be used as a limitation of the present invention.

[0034] like Figure 1 to Figure 2 As shown, the impact screwdriver 100 includes a housing 11, a motor 12, an output mechanism 13, a transmission mechanism 14 and an impact mechanism 15. The motor 12 includes a drive shaft 121 that rotates about the first axis 101. In this embodiment, the motor 12 is specifically configured as a motor, and the motor 12 will be used to replace the motor, and the motor shaft 121 will be used to replace the drive shaft, but this cannot be used as a limitation to the present application.

[0035] The output mechanism 13 includes an output shaft 131 for connecting a working accessory and driving the working accessory to rotate. A clamping assembly 132 is provided at the front end of the output shaft 131, which can clamp corresponding working accessories, such as screwdrivers, drill bits, sleeves, etc., when implementing different functions.

[0036] The output shaft 131 is used to output torque to operate the fastener. The output shaft 131 rotates around the output axis 102. In this embodiment, the first axis 101 coincides with the output axis 102. In other alternative embodiments, the output axis 102 is arranged at a certain angle to the first axis 101. In other alternative embodiments, the first axis 101 and the output axis 102 are arranged parallel to each other but do not coincide.

[0037] The impact mechanism 15 is used to apply an impact force to the output shaft 131. The impact mechanism 15 includes a main shaft 151, an impact block 152 sleeved on the outer periphery of the main shaft 151, an anvil 153 and an elastic element 154 arranged at the front end of the impact block 152. Among them, the anvil 153 is connected to the output shaft 131. In this embodiment, the anvil 153 includes an anvil seat, and the output shaft 131 is formed at the front end of the anvil seat. It can be understood that the anvil seat and the output shaft 131 can be integrally formed or separately formed as independent parts.

[0038] The elastic element 154 provides a force for the impact block 152 to approach the anvil 153. In this embodiment, the elastic element 154 is a coil spring.

[0039] The housing 11 includes a motor housing 111 for accommodating the motor 12 and an output housing 112 for accommodating at least part of the output assembly 13, and the output housing 112 is connected to the front end of the motor housing 111. The housing 11 is also formed or connected with a grip portion 113 for user operation. The grip portion 113 and the motor housing 112 form a T-shaped or L-shaped structure, which is convenient for the user to hold and operate. One end of the grip portion 113 is connected to the battery pack 30.

[0040] The transmission mechanism 14 is disposed between the motor 12 and the impact mechanism 15, and is used to realize the transmission of power between the motor shaft 121 and the main shaft 151. In this embodiment, the transmission mechanism 14 adopts a planetary gear reduction. Because the working principle of the planetary gear reduction and the reduction generated by this transmission mechanism have been fully disclosed to professionals in this field, a detailed description is omitted here for the purpose of brevity of the specification.

[0041] like Figure 1-3 As shown, the motor 12 includes a stator winding and a rotor. In some embodiments, the motor 12 is a three-phase brushless motor, including a rotor with permanent magnets and three-phase stator windings U, V, and W that are electronically commutated. In some embodiments, the three-phase stator windings U, V, and W are star-connected, and in other embodiments, the three-phase stator windings U, V, and W are angle-connected. However, it must be understood that other types of brushless motors are also within the scope of the present disclosure. The brushless motor may include less than or more than three phases.

[0042] The impact screwdriver 100 includes a control mechanism 17a. The control mechanism 17a includes a drive circuit 171 and a controller 17. The drive circuit 171 is electrically connected to the stator windings U, V, and W of the motor 12, and is used to transfer the current from the battery pack 30 to the stator windings U, V, and W to drive the motor 12 to rotate. In one embodiment, the drive circuit 171 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate terminal of each switching element is electrically connected to the controller 17 for receiving a control signal from the controller 17. The drain or source of each switching element is connected to the stator windings U, V, and W of the motor 12. The switch elements Q1-Q6 receive the control signal from the controller 17 to change their respective conduction states, thereby changing the current loaded by the battery pack 30 on the stator windings U, V, and W of the motor 12. In one embodiment, the drive circuit 171 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., field effect transistors (FET), bipolar junction transistors (BJT), insulated gate bipolar transistors (IGBT), etc.). It is understood that the above-mentioned switching elements may also be any other type of solid-state switches, such as insulated gate bipolar transistors (IGBT), bipolar junction transistors (BJT), etc.

[0043] In this embodiment, the controller 17 is used to control the motor 12. The controller 17 is arranged on a control circuit board, and the control circuit board includes: a printed circuit board (PCB) and a flexible printed circuit (FPC). The controller 17 uses a dedicated control chip, for example, a single chip microcomputer, a microcontroller unit (MCU). The controller 17 specifically controls the on or off state of the switch element in the drive circuit 171 through the control chip. In some embodiments, the controller 17 controls the ratio between the on time and the off time of the drive switch based on a pulse width modulation (PWM) signal. It should be noted that the control chip can be integrated into the controller 17, or it can also be set independently of the controller 17. As for the structural relationship between the drive chip and the controller 17, this embodiment does not limit it.

[0044] The impact screwdriver 100 further includes a power switch 16 and a switching portion 163. The power switch 16 is disposed on the grip portion 113 for user operation. The power switch 16 is used to control the power-on state of the motor 12. The switching portion 163 is disposed on the upper side of the main switch 16, and the switching portion 163 is configured to be operated to set the rotation direction of the motor 12 to a forward direction for tightening or screwing in a fastener or a reverse direction for loosening or screwing out a fastener.

[0045] In the present embodiment, the power switch 16 is a travel switch, wherein the travel switch includes an operating member 161 and a sliding rheostat 162 for operation. Therefore, the power switch 16 can also adjust the rotation speed of the motor 12. The rotation speed of the motor 12 is adjusted according to the trigger stroke of the operating member 161. The signal output by the sliding rheostat 162 is different when the trigger stroke of the operating member 161 is different. The trigger stroke of the operating member 161 is positively correlated with the duty cycle of the PWM signal of the motor 12, and the duty cycle of the PWM signal is positively correlated with the rotation speed of the motor 12. When the trigger stroke of the trigger switch is small, the duty cycle of the PWM signal is also small, and at this time, the rotation speed of the motor 12 is also small.

[0046] In some embodiments, the impact screwdriver 100 stores a mapping relationship between the trigger stroke of the operating member 161 and the PWM signal. The mapping relationship may be linear or non-linear, which is not limited in the embodiments of the present application.

[0047] The impact screwdriver 100 includes at least a first control mode and a second control mode. In the first control mode, the controller 17 is configured to control the maximum output speed of the motor 12 to be the first speed, and in response to the running state of the motor 12 reaching the first limiting condition, the speed of the motor 12 is limited to the non-driving speed, and in response to the speed of the motor 12 being the non-driving speed, the motor 12 operates at the second speed and drives the output shaft 131 to output torque, the second speed is less than the first speed, and the non-driving speed is less than the second speed. It should be explained that the maximum output speed of the motor 12 in "the maximum output speed of the motor 12 is the first speed" is: in the first control mode, when the trigger stroke of the operating member 161 of the power switch 16 is triggered to the limit stroke, the maximum speed output by the motor 12. The non-driving speed of the motor is: when the motor runs at the non-driving speed, the output shaft 131 cannot drive the fastener, which includes the motor 12 being stopped, that is, the speed is 0rpm, and the motor is limited to a speed close to the shutdown so that it cannot drive the fastener. The motor 12 operates at the second speed, which may include automatically restarting at the second speed after the motor stops, that is, the speed reaches 0rpm, and automatically operating at the second speed after the motor is limited to a speed close to the stop. In this embodiment, after the output of the motor 12 is limited, the motor 12 operates at the second speed, and the two stages of operation are performed continuously or at short intervals. In some embodiments, the interval between the two stages is less than or equal to 0.4s. At the same time, the user does not need to give a start signal again between the two stages, that is, the user does not need to give a stop signal before giving a start signal, or the user does not need to change the operation action.

[0048] In this embodiment, the running state of the motor 12 reaches the first limiting condition, which includes: after determining that the fastener operated by the output shaft 131 is in the first set state according to the output shaft load, the motor 12 drives the output shaft 131 to move to the position according to the preset condition.

[0049] The motor 12 drives the output shaft 131 to move into position according to the preset conditions, including: the number of rotations of the motor 12 driving the output shaft 131 reaches the preset number of rotations, or the rotation time of the motor 12 driving the output shaft 131 reaches the preset time, or the axial displacement of the output shaft 131 reaches at least one of the preset displacements. When the running state of the motor 12 reaches the first limiting condition, the motor 12 is controlled to stop or nearly stop and then automatically restart at a low speed, so that the user can accurately control the stop position of the screw 50 and improve the success rate of the screw 50 being flush with the target workpiece. Compared with the control logic of the related art that directly stops automatically after recognizing a certain state, the control scheme of the present application restarts at a low speed after stopping automatically, which can be applied to more working conditions, has simpler recognition conditions, and high control robustness.

[0050] When entering the first control mode, the maximum value of the output speed of the motor 12 is limited to 70% or less of the maximum speed of the motor 12, that is, the first speed is less than or equal to 70% of the maximum speed of the motor 12. In some embodiments, the first speed is less than or equal to 60% of the maximum speed of the motor 12. At this time, the stroke of the operating member 161 of the power switch 16 corresponds to the output speed of the motor 12. In some embodiments, the motor 12 starts working at the second speed and keeps driving the output shaft 131 to output torque at the first speed, and the second speed is less than or equal to 50% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 40% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 30% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 20% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 10% of the maximum speed of the motor 12. In some embodiments, the second speed is equal to 5% of the maximum speed of the motor 12. When starting at low speed, the motor 12 is controlled to keep working at the second speed at a constant speed, which is more conducive to the user to judge whether the screw 50 is flush.

[0051] As an embodiment, the fastener is a screw 50, and the target workpiece is a gypsum board 41 and a metal plate 42. Figure 4 As shown in FIG. 5 , it is a schematic diagram of the process of fastening the gypsum board 41 to a material plate (such as a metal plate 42) having a higher hardness than the gypsum board 41 using screws 50. Figure 5As shown, it is a schematic diagram of the process current (I) and the change with time (T) when the gypsum board 41 and the metal plate 42 are fastened by the screw 50. The screw 50 includes a screw head 51, a threaded portion 52 and a piercing portion 53. The process of fastening the gypsum board 41 and the metal plate 42 by using the screw 50 is generally divided into three stages; among which, the first stage is the P1 stage, the stage in which the threaded portion 52 and the piercing portion 53 enter the gypsum until the piercing portion 53 contacts the metal plate 42 (for example, an iron plate). In this stage, the load on the output shaft 131 gradually increases as the depth of the threaded portion 52 entering the gypsum board 41, and the output current of the motor 12 gradually increases. The output speed is controlled by setting a fixed duty cycle according to the voltage of the motor 12, and the output speed of the motor 12 gradually decreases in this stage. The second stage is the P2 stage, the stage in which the piercing portion 53 penetrates the metal plate 42 (for example, an iron plate). Since the hardness of the metal plate 42 is greater than that of the gypsum board 41, at the time point when the piercing portion 53 penetrates the metal plate 42, the load on the output shaft 131 is the largest, and even a sudden change occurs. At this stage, the output current of the motor 12 is the largest, and the current decreases after the piercing portion 53 penetrates the metal plate 42. The third stage is the P3 stage, and the screw 50 fastens the gypsum board 41 and the metal plate 42 to the stage of being fastened in place. Since the contact length between the metal plate 42, the gypsum board 41 and the threaded portion 52 is almost unchanged at this stage, until the top of the screw head 51 is flush with the gypsum board 41. Therefore, in the process of gradually screwing in, the load on the output shaft 131 does not basically change or fluctuate in amplitude. The output current of the motor 12 will first drop from the maximum value of the second stage P2 stage.

[0052] In this embodiment, after the controller 17 enters the first control mode, the controller 17 controls the motor 12 to drive the output shaft 131 to rotate at a speed less than or equal to the first speed to drive the screw 50 into the gypsum board 41. After the controller 17 determines that the screw 50 penetrates the metal plate 42 (such as an iron plate) according to the current-related parameters of the motor 12, the motor 12 drives the output shaft 131 to rotate a fixed number of circles, and then the controller 17 sends a stop signal to the motor 12 so that the output shaft 131 cannot drive the screw 50 to rotate. Among them, the fixed number of rotations of the output shaft 131 is pre-calibrated or corresponds to the number of rotations of the output shaft 131 according to the current-related parameters of the motor 12 through a table lookup method. Then the controller 17 controls the motor 12 to automatically start and output torque at the second speed, and controls the motor to stop when the user outputs a stop signal. In this embodiment, after the motor 12 automatically starts at the second speed, it maintains a constant speed, that is, the trigger stroke of the operating member 161 of the power switch 16 does not affect the speed of the motor 12. In some embodiments, after the motor 12 is automatically started at the second speed, the speed of the motor 12 can be adjusted by the trigger stroke of the operating member 161 of the power switch 16, but at this stage the maximum speed when the trigger stroke of the operating member 161 of the power switch 16 reaches the limit is still less than or equal to the first speed.

[0053] Since the load of the output shaft 131 remains basically unchanged after the screw 50 penetrates the metal plate 42, the output of the output shaft 131 at a low speed and constant speed can enable the user to accurately control the stop position of the screw 50 and improve the success rate of the screw 50 being flush with the target workpiece. Compared with the control logic of the related art that directly stops automatically after recognizing a certain state, the control scheme of the present application restarts at a low speed after stopping, which can be applied to more working conditions, has simpler recognition conditions, and has high control robustness.

[0054] In this embodiment, the second speed is less than or equal to 3000 rpm. In some embodiments, the second speed is less than or equal to 2000 rpm. In some embodiments, the second speed is less than or equal to 1500 rpm. In this embodiment, the duty cycle is adjusted by the PID (proportional P, integral I, differential control D) controller 17 to ensure that the motor 12 runs at a constant speed at the second speed.

[0055] In this embodiment, the controller 17 sends a stop signal to the motor 12, and the motor 12 uses rapid braking (for example, three-phase short circuit), that is, from the time the stop signal is sent to the controller 17 to the time when the speed of the motor 12 is 0 or close to 0, the output shaft 131 will basically not rotate the fastener more than one circle, so as to avoid the influence of the speed reduction process on the screwing in of the screw 50.

[0056] In this embodiment, the number of rotations of the output shaft 131 driven by the motor 12 is represented by the commutation information of the motor 12. The commutation information of the motor 12 includes: at least one of the commutation starting point, the commutation end point, or the time required to complete each commutation. When the duty cycle of the drive signal of the motor 12 is fixed, the greater the load on the output shaft 131, the smaller the rotation angle of the output shaft 131 caused by the impact force each time an impact occurs. The number of rotations of the drive shaft of the motor 12 is related to the number of rotations or the rotation angle of the output shaft 131. The number of commutations of the motor 12 is related to the number of rotations of the drive shaft of the motor 12, so the parameters of the commutation of the motor 12 can represent the number of rotations of the output shaft 131 or the rotation angle of the output shaft 131.

[0057] Taking the three-phase brushless motor 12 in this embodiment as an example, the drive circuit includes six drive states. By turning on different combinations of upper and lower bridge arm switch elements, the direction of current flow can be controlled, magnetic fields in different directions can be generated, and the permanent magnet rotor can be rotated to a specified position. When the drive circuit switches from one drive state to another drive state, the motor 12 performs a phase change. There are three switch elements in each upper and lower bridge arm, and a total of six combinations. Therefore, it changes once every 60°, and after six steps of phase change, the motor 12 can rotate an electrical cycle. It should be explained that an electrical cycle may not correspond to a complete rotor mechanical rotation cycle. The number of electrical cycles to be repeated to complete a mechanical rotation depends on the number of magnetic pole pairs of the rotor. In the phase change detection of the motor 12, in some embodiments, a Hall element is used to detect the magnetic field of the rotor. The phase change information of the motor 12 is obtained by detecting the Hall sensor. In some embodiments, the motor 12 is not provided with a sensor element. By detecting the induced voltage of the motor 12 generated by the back electromotive force, the waveform change of the back electromotive force voltage signal of each phase indicates the phase change of the motor 12. Because the working principles of detecting the commutation of the motor 12 using sensors and without sensors have been fully disclosed to professionals in this field, a detailed description is omitted here for the purpose of brevity.

[0058] When the number of rotations of the output shaft 131 is detected, the starting point of the phase change of the motor 12 is detected as an example. Each time the starting point of the phase change of the motor 12 is detected, the number of phase changes is increased by 1, and the total number of phase changes is accumulated. The controller 17 stores the corresponding relationship between the total number of phase changes and the number of rotations of the output shaft 131. When the number of rotations of the output shaft 131 corresponding to the total number of phase changes reaches the preset number of rotations, the motor 12 is controlled to stop.

[0059] In some embodiments, after the controller 17 determines that the screw 50 penetrates the metal plate 42 (e.g., iron plate) according to the current-related parameters of the motor 12, and the motor 12 drives the output shaft 131 to rotate for a preset time, the controller 17 sends a stop signal to the motor 12 so that the output shaft 131 cannot rotate while driving the screw 50. The preset rotation time of the output shaft 131 is pre-calibrated or corresponds to the rotation time of the output shaft 131 according to the current-related parameters of the motor 12 by a table lookup method. The rotation time of the output shaft 131 can be characterized by the running time of the motor 12. Timing is performed by setting a timer or a timing module in the controller 17.

[0060] In some embodiments, after the controller 17 determines that the screw 50 penetrates the metal plate 42 (e.g., iron plate) according to the current-related parameters of the motor 12, and the axial displacement of the output shaft 131 driven by the motor 12 reaches a preset displacement, the controller 17 sends a stop signal to the motor 12 so that the output shaft 131 cannot rotate while driving the screw 50. The preset displacement of the axial displacement of the output shaft 131 is pre-calibrated or corresponds to the axial displacement of the output shaft 131 according to the current-related parameters of the motor 12 by a table lookup method. The axial displacement of the output shaft 131 can be measured using a position sensor.

[0061] In this embodiment, the control mechanism 17a further includes a first detection component 181 for detecting a preset condition parameter of the output shaft 131. For example, the Hall sensor, timer or position sensor mentioned above. In some embodiments, the first detection component 181 includes an attenuator and a low pass filter (LPF) to measure the back electromotive force voltage.

[0062] By comparing the load parameter of the output shaft 131 with the first threshold, it is determined that the fastener is in the first setting state. In this embodiment, the first setting state of the fastener is that the screw 50 penetrates the metal plate 42. The first threshold is a pre-calibrated value.

[0063] In this embodiment, a second detection component 182 is further included for detecting the load parameters of the output shaft 131. In this embodiment, the load parameters of the output shaft 131 include parameters related to the current of the motor 12. It should be explained that the parameters related to the current of the motor 12 include the current of the motor 12 and the parameters obtained by calculating the current of the motor 12. The second detection component 182 includes a current sensing resistor, a Hall current sensor or a mosfet (metal oxide semiconductor field effect transistor) on-resistance.

[0064] In some embodiments, the load parameters of the output shaft 131 include parameters related to the speed of the motor 12. It should be explained that the parameters related to the speed of the motor 12 include the speed of the motor 12 and the parameters obtained by calculating the speed of the motor 12, such as the torque of the motor 12. When the load of the output shaft 131 is large, the speed of the output shaft 131 decreases, and the speed of the motor 12 also decreases. When the load of the output shaft 131 is small, the speed of the output shaft 131 increases, and the speed of the motor 12 also increases.

[0065] The rotation speed of the motor 12 is detected by a magnetic ring, a magnetic steel or a photoelectric encoder, and by an inductor, a Hall sensor or a photoelectric sensor.

[0066] In some embodiments, the load parameter of the output shaft 131 is characterized by the rotation parameter of the output shaft 131. The rotation parameter of the output shaft 131 includes at least one parameter of the rotation speed of the output shaft 131, the rotation angle of the output shaft 131, and the rotation acceleration of the output shaft 131. The second detection component 182 is used to detect the rotation parameter of the output shaft 131. The second detection component 182 includes a position sensor, which can be a photodiode sensor, a magnetic sensor, or a potentiometer. The second detection component 182 can also be a rotation sensor, specifically a gyroscope sensor. The gyroscope sensor can be a single-axis, two-axis, or three-axis micro-electromechanical system (MEMS) sensor or a rotation sensor. Among them, when the parameters detected by the first detection component 181 and the second detection component 182 are the same, the first detection component 181 and the second detection component 182 can also be merged.

[0067] When the impact screwdriver 100 is in the first control mode, the motor 12 receives a stop command, and the controller 17 controls the motor 12 to stop. When the motor 12 receives the start signal again, it is determined that the difference t1 between the time when the motor 12 receives the start signal and the time when the motor 12 receives the stop command is less than or equal to the first time parameter t, and the impact screwdriver 100 enters the second control mode. In the second control mode, the controller 17 limits the output of the motor and does not perform the control of the first control mode. In this way, the motor 12 will still run at a low speed when it is restarted again in a short time after exiting the low speed mode. In this embodiment, in the second control mode, the maximum value of the output speed of the motor 12 is less than or equal to 70% of the maximum output speed of the motor 12, and the stroke of the power switch 16 corresponds to the output speed of the motor 12. In this way, when the user is not sure whether the fastener is in place, even if the user stops the machine to check the fastener status, the motor 12 will still start at a low speed when it is restarted again in a short time. When t1 is greater than the first time parameter t, the second control mode is not entered, and the corresponding control logic is corresponding to the current setting of the impact screwdriver 100.

[0068] In this embodiment, the first time parameter is 0.5s. In some embodiments, the first time parameter is 0.6s, 0.7s, 0.8s, 0.9s, or 1.0s.

[0069] In the present embodiment, the impact screwdriver 100 includes a mode selection unit, and the impact screwdriver 100 includes a first gear mode, a second gear mode or more other modes, and these different gear modes are set for different target workpieces, or fasteners, or certain special working conditions. Among them, the first control mode and the second control mode are both partial control modes under the first gear mode. The activation condition of the first control mode includes first selecting the first gear mode, and when the displacement stroke of the operating member 161 of the power switch 16 in the first gear mode meets the preset stroke, the first control mode is activated. In the present embodiment, when the displacement stroke of the operating member 161 of the power switch 16 is greater than 50% of the total stroke, the first control mode is activated.

[0070] In some embodiments, the first control mode and the second control mode are also used in the second gear mode. In some embodiments, the first control mode and the second control mode are also used in other modes. The above does not affect the substantive content of this application.

[0071] like Figure 6 As shown, this embodiment also discloses a control method for an impact tool, which specifically includes: S110: Control the maximum output speed of the motor 12 to be a first speed.

[0072] S120: Determine whether the operating state of the motor 12 reaches a first limiting condition.

[0073] S130: Limiting the rotation speed of the motor to a non-driving rotation speed so that the output shaft 131 cannot drive the fastener.

[0074] S140: The motor 12 operates at a second speed and drives the output shaft 131 to output torque, the second speed is lower than the first speed, and the non-driving speed is lower than the second speed.

[0075] By using the output of the low-speed rotation control output shaft 131, the user can accurately control the stop position of the screw 50, and improve the success rate of the screw 50 being flush with the target workpiece. Compared with the control logic of the related art that directly stops automatically after recognizing a certain state, the control scheme of the present application restarts at a low speed after stopping, which can be applied to more working conditions, has simpler recognition conditions, and has high control robustness.

[0076] like Figure 7 As shown, this embodiment also discloses another control method of an impact tool, which specifically includes: S210: Switch the impact screwdriver 100 to the first gear mode.

[0077] S220: Determine whether the displacement stroke of the operating member 161 of the power switch 16 meets the preset stroke. If so, execute S240; if not, execute S230.

[0078] S230: Exit the first gear mode.

[0079] S240: Activate the first gear mode and control the motor 12 to run at a speed less than or equal to the first rotation speed.

[0080] When entering the first control mode, the maximum value of the output speed of the motor 12 is limited to 70% or less of the maximum speed of the motor 12. At this time, the displacement stroke of the operating member 161 of the power switch 16 corresponds to the output speed of the motor 12.

[0081] S250: Determine whether the screw 50 has penetrated the metal plate 42 according to the current-related parameters of the motor 12; if so, execute S260; if not, execute S240.

[0082] The load parameter of the output shaft 131 is characterized according to the current-related parameter of the motor 12, and by comparing the load parameter of the output shaft 131 with the first threshold, it is determined that the screw 50 penetrates the metal plate 42. At the same time, the load parameter of the output shaft 131 can also be characterized according to at least one parameter of the speed-related parameter of the motor 12, the speed of the output shaft 131, the rotation angle of the output shaft 131, and the rotation acceleration of the output shaft 131.

[0083] S260: The motor 12 drives the output shaft 131 to rotate a fixed number of revolutions.

[0084] The number of rotations of the output shaft 131 is pre-calibrated or matched to the number of rotations of the output shaft 131 by a table lookup method according to the current-related parameters of the motor 12. By using a 25 mm long screw 50 and a 10 mm thick gypsum board 41, the test screw 50 is screwed into a thickness of about 15 mm, and the standard threshold is determined according to the number of threads of the screw 50 within 15 mm, and then adjusted according to the feel of actual operation.

[0085] In some embodiments, the motor 12 drives the output shaft 131 to rotate for a preset time, or the axial displacement of the output shaft 131 reaches a preset displacement. The preset time and the preset displacement are also pre-calibrated or correspond to the rotation time and displacement of the output shaft 131 according to the current-related parameters of the motor 12 through a table lookup method.

[0086] S270: Send a stop signal to the motor 12 so that the output shaft 131 cannot drive the screw 50 to rotate.

[0087] The controller 17 sends a stop signal to the motor 12, and the motor 12 uses rapid braking, that is, from the time the stop signal is sent to the controller 17 to the time when the speed of the motor 12 is 0 or close to 0, the output shaft 131 will basically not rotate the screw 50 more than one circle, so as to avoid the influence of the speed reduction process on the screwing in of the screw 50.

[0088] S280: Control the motor 12 to automatically operate at a second speed and output torque, wherein the second speed is lower than the first speed.

[0089] In this embodiment, after the motor 12 is automatically started at the second speed, it maintains constant speed operation. In some embodiments, after the motor 12 is automatically started at the second speed, the speed of the motor 12 can be adjusted by the trigger stroke of the operating member 161 of the power switch 16, but at this stage, the maximum speed when the trigger stroke of the operating member 161 of the power switch 16 reaches the limit is still less than or equal to the first speed.

[0090] The second speed is less than or equal to 50% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 40% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 30% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 20% of the maximum speed of the motor 12. In some embodiments, the second speed is less than or equal to 10% of the maximum speed of the motor 12. In some embodiments, the second speed is equal to 5% of the maximum speed of the motor 12. The duty cycle is adjusted by the PID (proportional P, integral I, differential control D) controller 17 to ensure that the motor 12 runs at a constant speed at the second speed.

[0091] S290: The user outputs a shutdown signal; if yes, execute S291, if not, execute S280.

[0092] S291: End.

[0093] like Figure 8 As shown, this embodiment also discloses a third control method for an impact tool, which specifically includes: S210: Switch the impact screwdriver 100 to the first gear mode.

[0094] S220: Determine whether the displacement stroke of the operating member 161 of the power switch 16 meets the preset stroke. If so, execute S240; if not, execute S230.

[0095] S230: Exit the first gear mode.

[0096] S240: Activate the first gear mode and control the motor 12 to run at a speed less than or equal to the first rotation speed.

[0097] When entering the first control mode, the maximum value of the output speed of the motor 12 is limited to 70% or less of the maximum speed of the motor 12. At this time, the displacement stroke of the operating member 161 of the power switch 16 corresponds to the output speed of the motor 12.

[0098] S250: Determine whether the screw 50 has penetrated the metal plate 42 according to the current-related parameters of the motor 12; if so, execute S260; if not, execute S240.

[0099] The load parameter of the output shaft 131 is characterized according to the current-related parameter of the motor 12, and by comparing the load parameter of the output shaft 131 with the first threshold, it is determined that the screw 50 penetrates the metal plate 42. At the same time, the load parameter of the output shaft 131 can also be characterized according to at least one parameter of the speed-related parameter of the motor 12, the speed of the output shaft 131, the rotation angle of the output shaft 131, and the rotation acceleration of the output shaft 131.

[0100] S260: The motor 12 drives the output shaft 131 to rotate a fixed number of revolutions.

[0101] The number of rotations of the output shaft 131 is pre-calibrated or matched to the number of rotations of the output shaft 131 by a table lookup method according to the current-related parameters of the motor 12. By using a 25 mm long screw 50 and a 10 mm thick gypsum board 41, the test screw 50 is screwed into a thickness of about 15 mm, and the standard threshold is determined according to the number of threads of the screw 50 within 15 mm, and then adjusted according to the feel of actual operation.

[0102] In some embodiments, the motor 12 drives the output shaft 131 to rotate for a preset time, or the axial displacement of the output shaft 131 reaches a preset displacement. The preset time and the preset displacement are also pre-calibrated or correspond to the rotation time and displacement of the output shaft 131 according to the current-related parameters of the motor 12 through a table lookup method.

[0103] S270: Send a stop signal to the motor 12 so that the output shaft 131 cannot drive the screw 50 to rotate.

[0104] The controller 17 sends a stop signal to the motor 12, and the motor 12 uses rapid braking, that is, from the time the stop signal is sent to the controller 17 to the time when the speed of the motor 12 is 0 or close to 0, the output shaft 131 will basically not rotate the screw 50 more than one circle, so as to avoid the influence of the speed reduction process on the screwing in of the screw 50.

[0105] S280: Control the motor 12 to automatically operate at a second speed and output torque, wherein the second speed is lower than the first speed.

[0106] In this embodiment, after the motor 12 is automatically started at the second speed, it maintains constant speed operation. In some embodiments, after the motor 12 is automatically started at the second speed, the speed of the motor 12 can be adjusted by the trigger stroke of the operating member 161 of the power switch 16, but at this stage, the maximum speed when the trigger stroke of the operating member 161 of the power switch 16 reaches the limit is still less than or equal to the first speed.

[0107] The second speed is less than or equal to 50% of the maximum speed of the motor 12. In some embodiments, the first speed is less than or equal to 40% of the maximum speed of the motor 12. In some embodiments, the first speed is less than or equal to 30% of the maximum speed of the motor 12. In some embodiments, the first speed is less than or equal to 20% of the maximum speed of the motor 12. In some embodiments, the first speed is less than or equal to 10% of the maximum speed of the motor 12. In some embodiments, the first speed is equal to 5% of the maximum speed of the motor 12. The duty cycle is adjusted by the PID (proportional P, integral I, differential control D) controller 17 to ensure that the motor 12 runs at a constant speed at the first speed.

[0108] S290: The user outputs a shutdown signal; if yes, execute S291, if not, execute S280.

[0109] S291: Impact screwdriver 100 stops.

[0110] S300: The motor 12 receives the start signal again.

[0111] S310: Determine whether the time difference t1 between the time when the motor 12 receives the start signal and the time when the motor 12 receives the stop command is less than or equal to the first time parameter t. If so, execute S320; if not, execute S330.

[0112] The first time parameter is 0.5s. In some embodiments, the first time parameter is 0.6s, 0.7s, 0.8s, 0.9s, or 1.0s.

[0113] S320: The controller 17 limits the output speed of the motor and does not perform the control of the first control mode. When a stop command is received, the process returns to S291.

[0114] S330: Do not enter the second control mode, and correspond to the corresponding control logic according to the current setting of the impact screwdriver 100.

[0115] As some embodiments of the present application, the substantive content of the technical solution disclosed above can also be applied to other electric tools that are driven by a motor and have an output shaft that outputs torque but do not have an impact component. For example, the electric tool can be a screwdriver, an electric drill, or a wrench. The present application does not limit the type of electric tool. As long as the electric tool can adopt the substantive content of the technical solution disclosed above, it can fall within the protection scope of the present application.

[0116] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An impact tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, driven by the motor, and used to output torque to the outside; The output shaft rotates with the output axis as the rotation axis; An impact mechanism for applying an impact force to the output shaft; the impact mechanism comprises: an impact block driven by the drive shaft and an anvil receiving an impact from the impact block; the output shaft is formed or connected to the anvil; A controller, used for controlling the motor; Wherein, the controller includes a first control mode; when entering the first control mode, the controller is configured as follows: The maximum output speed of the motor is controlled to be a first speed. In response to the operating state of the motor reaching a first limiting condition, the speed of the motor is limited to a non-driving speed. In response to the speed of the motor being the non-driving speed, the motor operates at a second speed to drive the output shaft to output torque, and the second speed is less than the first speed, and the non-driving speed is less than the second speed.

2. The impact tool according to claim 1, characterized in that The running state of the motor reaches the first limiting condition comprising: after determining that the fastener operated by the output shaft is in a first set state according to the load parameter of the output shaft, the motor drives the output shaft to move to a position according to a preset condition.

3. The impact tool according to claim 2, characterized in that The motor drives the output shaft to move into position under the preset conditions, including: the number of rotations driven by the motor to the output shaft reaches a preset number of rotations, or the rotation time driven by the motor to the output shaft reaches a preset time, or the axial displacement of the output shaft reaches at least one of a preset displacement amount.

4. The impact tool according to claim 2, characterized in that The load parameter of the output shaft includes at least one of a speed-related parameter of the motor and a current-related parameter of the motor.

5. The impact tool according to claim 2, characterized in that: The load parameter of the output shaft includes at least one parameter of a rotation speed of the output shaft, a rotation angle of the output shaft, and a rotation acceleration of the output shaft.

6. The impact tool according to claim 3, characterized in that The number of rotations of the output shaft driven by the motor is represented by the commutation information of the motor.

7. The impact tool according to claim 6, characterized in that The commutation information of the motor includes: at least one of a commutation starting point, a commutation ending point, or a time required to complete each commutation.

8. The impact tool according to claim 1, characterized in that When the motor runs at the second speed, the motor receives a stop command, and the controller controls the motor to stop. When the motor receives a start signal again, it is determined that the difference between the time when the motor receives the start signal and the time when the motor receives the stop command is less than or equal to the first time parameter, and the impact tool enters the second control mode.

9. The impact tool according to claim 8, characterized in that In the second control mode, the controller limits the output of the motor, and the controller does not perform the control in the first control mode.

10. The impact tool according to claim 1, characterized in that The impact tool comprises a power switch for receiving a user's power-on command and a power-off command. When the power switch is set to a preset state, the controller enters a first control mode.

11. The impact tool according to claim 10, characterized in that The power switch includes a travel switch, and when the displacement travel of the travel switch meets a preset travel, the controller enters a first control mode.

12. An impact tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, driven by the motor, and used to output torque to the outside; The output shaft rotates with the output axis as the rotation axis; An impact mechanism for applying an impact force to the output shaft; the impact mechanism comprises: an impact block driven by the drive shaft and an anvil receiving an impact from the impact block; the output shaft is formed or connected to the anvil; A controller, used for controlling the motor; Wherein, the controller includes a first control mode; when entering the first control mode, the controller is configured as follows: In response to the operating state of the motor reaching a first limiting condition, the speed of the motor is limited to a non-driving speed. In response to the speed of the motor being the non-driving speed, the motor operates at a second speed and maintains the second speed to drive the output shaft to output torque. The second speed is less than or equal to 50% of the maximum speed of the motor, and the non-driving speed is less than the second speed.

13. An electric tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, driven by the motor, used to output torque to the outside; the output shaft rotates with the output axis as the rotation axis; A controller, used for controlling the motor; Wherein, the controller includes a first control mode; when entering the first control mode, the controller is configured to: control the maximum output speed of the motor to be a first speed, in response to the operating state of the motor reaching a first limiting condition, limit the speed of the motor to a non-driving speed, in response to the speed of the motor being the non-driving speed, the motor operates at a second speed to drive the output shaft to output torque, the second speed is less than the first speed, and the non-driving speed is less than the second speed.

14. A method for controlling an impact tool, characterized in that: The impact tool comprises: a motor including a drive shaft that rotates about a first axis; An output shaft, driven by the motor, used to output torque to the outside; the output shaft rotates with the output axis as the rotation axis; An impact mechanism for applying an impact force to the output shaft; the impact mechanism comprises: an impact block driven by the drive shaft and an anvil receiving an impact from the impact block; the output shaft is formed or connected to the anvil; A controller, used for controlling the motor; Wherein, the controller includes a first control mode; when entering the first control mode, the control method includes the following steps: Controlling the maximum output speed of the motor to be a first speed; Determining that the motor operating state reaches a first limiting condition; limiting the speed of the motor to a non-driving speed; The motor operates at a second speed and drives the output shaft to output torque, the second speed is lower than the first speed, and the non-driving speed is lower than the second speed.

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