CN119328699A

CN119328699A - Impact tool, electric tool and control method

Info

Publication number: CN119328699A
Application number: CN202410941329.1A
Authority: CN
Inventors: 刘龙翔; 吴勇慷; 张彪
Original assignee: Nanjing Chervon Industry Co Ltd
Current assignee: Nanjing Chervon Industry Co Ltd
Priority date: 2023-07-20
Filing date: 2024-07-12
Publication date: 2025-01-21

Abstract

The application discloses an impact tool, an electric tool and a control method, wherein the impact tool comprises a controller for controlling a motor, the controller comprises a first control mode, when the first control mode is entered, 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 a non-driving rotating speed in response to the running state of the motor reaching a first limiting condition, and drive an output shaft to output torque by the motor at a second rotating speed after the rotating speed of the motor is the non-driving rotating speed, wherein the second rotating speed is smaller than the first rotating speed, and the non-driving rotating speed is smaller than the second rotating speed. More working conditions may be applicable.

Description

Impact tool, electric tool, and control method

Technical Field

The present application relates to an electric tool, and more particularly, to an impact tool, an electric tool, and a control method.

Background

In the electric tool in the related art, in the operation process, the electric tool adopts a motor to drive an output shaft to output torque outwards, so that a fastener is driven to rotate at a high speed and screwed into a target workpiece. When driving fasteners into a workpiece using a power tool, the power tool requires the user to be skilled in controlling the power tool so that the fastener can be flush with the workpiece, which places a relatively high demand on the ability of the user. In the related art, the power tool determines that the fastener works in place by identifying the working parameters of some power tools, and then stops the power tool. However, since the power tool operates the fastener and the target workpiece are of various kinds, it is difficult to accurately flush the fastener with the workpiece.

This section provides background information related to the application, which is not necessarily prior art.

Disclosure of Invention

It is an object of the present application to solve or at least mitigate some or all of the above problems. To this end, it is an object of the present application to provide an impact tool that facilitates control of the fastener installation level with the workpiece.

In order to achieve the above object, the present application adopts the following technical scheme:

An impact tool includes a motor including a drive shaft rotating about a first axis, an output shaft driven by the motor, the output shaft for outputting torque externally, the output shaft rotating about the output shaft as a rotational axis, an impact mechanism for applying an impact force to the output shaft, the impact mechanism including an impact block driven by the drive shaft and an anvil receiving an impact from the impact block, the output shaft being formed or connected to the anvil, and a controller for controlling the motor, wherein the controller includes a first control mode, and upon entering the first control mode, the controller is configured to control a maximum output rotational speed of the motor to a first rotational speed, limit the rotational speed of the motor to a non-driving rotational speed in response to an operational state of the motor reaching a first limit condition, and operate the output shaft to output torque at a second rotational speed in response to the rotational speed of the motor being the non-driving rotational speed, the second rotational speed being less than the first rotational speed, the non-driving rotational speed being less than the second rotational speed.

In some embodiments, the motor operating condition reaching the first limit condition includes the motor driving the output shaft to move in place in a preset condition after determining that the fastener operated by the output shaft is in a first set condition based on the load parameter of the output shaft.

In some embodiments, the motor driving the output shaft in place in the preset condition includes at least one of a number of turns of the motor driving the output shaft reaching a preset number of turns, a rotation time of the motor driving the output shaft reaching a preset time, or an axial displacement of the output shaft reaching a preset displacement.

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

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

In some embodiments, the number of turns of the motor drive output shaft is characterized by the commutation information of the motor.

In some embodiments, the commutation information for the motor includes at least one of a commutation start point, a commutation end point for each commutation, or a length of time required to complete each commutation.

In some embodiments, the controller controls the motor to stop when the motor is operated at the second rotational speed, and determines that a difference between a time when the motor receives the start signal and a time when the motor receives the stop command is less than or equal to a first time parameter when the motor receives the start signal again, the impact tool enters the second control mode.

In some embodiments, the controller limits the output of the motor in the second control mode while the controller does not perform the control in the first control mode.

In some embodiments, the impact tool includes a power switch for receiving a user start-up command and a stop command, and the controller enters the first control mode when the power switch is set in a preset state.

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

An impact tool includes a motor including a drive shaft rotating about a first axis, an output shaft driven by the motor and adapted to output torque externally, the output shaft rotating about the output axis, an impact mechanism including an impact block driven by the drive shaft and an anvil receiving an impact from the impact block, the output shaft forming or being connected to the anvil, and a controller adapted to control the motor, wherein the controller includes a first control mode, the controller being configured to, upon entering the first control mode, limit the output of the motor, and to operate the motor at a second rotational speed and to maintain the second rotational speed at or below 50% of a maximum rotational speed of the motor, after limiting the output of the motor.

An electric tool comprises a motor, an output shaft driven by the motor, the output shaft used for outputting torque externally, a controller used for controlling the motor, and a controller used for controlling the motor, wherein the controller comprises a first control mode, when the controller enters 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 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 after the rotating speed of the motor is the non-driving rotating speed, the second rotating speed is smaller than the first rotating speed, and the non-driving rotating speed is smaller than the second rotating speed.

A control method of an impact tool comprises the steps of a motor, an output shaft, an impact mechanism and a controller, wherein the motor comprises a driving shaft rotating around a first axis, the output shaft is driven by the motor and used for outputting torque externally, the output shaft rotates by taking the output axis as a rotating shaft, the impact mechanism comprises an impact block driven by the driving shaft and an anvil receiving impact from the impact block, the output shaft is formed or connected with the anvil, the controller is used for controlling the motor, the controller comprises a first control mode, when the first control mode is entered, the control method comprises the steps of controlling the maximum output rotating speed of the motor to be a first rotating speed, determining that the running state of the motor reaches a first limiting condition, controlling the motor to limit output, operating at a second rotating speed and driving the output shaft to output torque, and the second rotating speed is smaller than the first rotating speed.

A control method of an electric tool comprises the steps of a motor, an output shaft driven by the motor and used for outputting torque externally, a controller used for controlling the motor, wherein the output shaft rotates by taking an output axis as a rotating shaft, the controller comprises a first control mode, when the first control mode is entered, the control method comprises the steps of controlling the maximum output rotating speed of the motor to be a first rotating speed, determining that the running state of the motor reaches a first limiting condition, controlling the motor to limit output, operating the motor at a second rotating speed and driving the output shaft to output torque, and the second rotating speed is smaller than the first rotating speed.

The application has the advantages that the running state of the motor reaches the first limiting condition, the motor is controlled to the non-driving rotating speed, namely, the motor is stopped or limited to be close to the stopping, and the motor automatically works at a low speed, so that a user can accurately control the stopping position of the screw, and the success rate of the screw being leveled with a target workpiece is improved. Compared with the control logic for directly stopping after a certain state is identified in the related art, the control scheme of the application is restarted at a low speed after stopping, can be suitable for more working conditions, has simpler identification conditions and has high control robustness.

Drawings

FIG. 1 is a schematic diagram of an embodiment of the present application;

FIG. 2 is a schematic diagram of a cross-sectional view of a portion of the components of FIG. 1;

FIG. 3 is a circuit block diagram of one embodiment of the present application;

FIG. 4 is a schematic illustration of the process of fastening a gypsum board to a sheet of material (e.g., metal) having a higher hardness than the gypsum board using screws in accordance with the present application;

FIG. 5 is a schematic representation of the process current (I) versus time (T) of the fastening of gypsum board to metal board using screws in accordance with the present application;

FIG. 6 is a control flow diagram of the present application;

FIG. 7 is another control flow diagram of the present application;

fig. 8 is a third control flow chart of the present application.

Detailed Description

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 following drawings.

In the present disclosure, the terms "comprises," "comprising," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the present application, the term "and/or" is an association relationship describing an association object, meaning that three relationships may exist. For example, A and/or B may mean that A alone, both A and B, and B alone are present. In the present application, the character "/" generally indicates that the front and rear related objects are in an "and/or" relationship.

In the present application, the terms "connected," "coupled," and "mounted" may be directly connected, coupled, or mounted, or indirectly connected, coupled, or mounted. By way of example, two parts or components are connected together without intermediate members, and by indirect connection is meant that the two parts or components are respectively connected to at least one intermediate member, through which the two parts or components are connected. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings, and may include electrical connections or couplings.

In the present application, one of ordinary skill in the art will understand that relative terms (e.g., "about," "approximately," "substantially," etc.) used in connection with quantities or conditions are intended to encompass the values and have the meanings indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a particular value, the tolerance associated with a particular value resulting from manufacture, assembly, use, and the like. Such terms should also be considered to disclose a range defined by the absolute values of the two endpoints. Relative terms may refer to the addition or subtraction of a percentage (e.g., 1%,5%,10% or more) of the indicated value. Numerical values, not employing relative terms, should also be construed as having specific values of tolerance. Further, "substantially" when referring to relative angular positional relationships (e.g., substantially parallel, substantially perpendicular) may refer to adding or subtracting a degree (e.g., 1 degree, 5 degrees, 10 degrees, or more) from the indicated angle.

In the present application, those of ordinary skill in the art will appreciate that the functions performed by a component may be performed by a component, a plurality of components, a part, or a plurality of parts. Also, the functions performed by the elements may be performed by one element, by an assembly, or by a combination of elements.

In the present application, the terms "upper", "lower", "left", "right", "front", "rear", and the like are described in terms of orientation and positional relationship shown in the drawings, and should not be construed as limiting the embodiments of the present application. In the context of this document, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on the other element or be indirectly on the other element through intervening elements. It should also be understood that the terms upper, lower, left, right, front, back, etc. are not only intended to represent positive orientations, but also to be construed as lateral orientations. For example, the lower side may include a right lower side, a left lower side, a right lower side, a front lower side, a rear lower side, and the like.

In the present application, the terms "controller", "processor", "central processing unit", "CPU", "MCU" are interchangeable. Where a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a particular function, such function may be performed by a single unit or by a plurality of units unless otherwise indicated.

In the present application, the terms "means," "module," or "unit" may be implemented in hardware or software for the purpose of realizing a specific function.

In the present application, the terms "computing," "determining," "controlling," "determining," "identifying," and the like refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

Fig. 1 and 2 show an impact tool according to an embodiment of the application. The impact tool is an impact screw driver 100. It will be appreciated that in other alternative embodiments the impact tool may be fitted with different working attachments by means of which the impact tool may be, for example, a drill hammer, an impact wrench or the like.

The impact screw 100 includes a power supply. In the present embodiment, the power supply is a dc power supply 30. Dc power supply 30 is used to provide power to impact screw driver 100. The dc power supply 30 is a battery pack that cooperates with a corresponding power circuit to power the impact screw driver 100. It should be understood by those skilled in the art that the power supply is not limited to the use of a dc power supply, and may also be implemented to supply power to corresponding components in the machine by using a mains supply, an ac power supply, and corresponding rectifying, filtering and voltage regulating circuits. In the present embodiment, the dc power supply is a battery pack, and the battery pack 30 will be used instead of the dc power supply hereinafter, but this is not intended as a limitation of the present invention.

As shown in fig. 1 to 2, the impact screw 100 includes a housing 11, a motor 12, an output mechanism 13, a transmission mechanism 14, and an impact mechanism 15. Wherein the motor 12 comprises a drive shaft 121 rotating about a first axis 101. In the present embodiment, the motor 12 is specifically provided as a motor, and hereinafter, the motor 12 is replaced with a motor, and the drive shaft is replaced with a motor shaft 121, but this is not intended as a limitation of the present application.

The output mechanism 13 includes an output shaft 131 for connecting and driving the work attachment in rotation. The front end of the output shaft 131 is provided with a clamping component 132 which can clamp corresponding working accessories such as screwdrivers, drills, sleeves and the like when different functions are realized.

The output shaft 131 is used for outputting torque to the outside to operate the fastener, and the output shaft 131 rotates with the output axis 102 as a shaft, and in this embodiment, the first axis 101 coincides with the output axis 102. In other alternative embodiments, the output axis 102 is disposed at an 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 not coincident.

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 fitted around the outer periphery of the main shaft 151, an anvil 153 provided at the front end of the impact block 152, and an elastic member 154. Wherein an anvil 153 is coupled to the output shaft 131. In the present embodiment, the anvil 153 includes an anvil, and the output shaft 131 is formed at a front end of the anvil. It will be appreciated that the anvil and output shaft 131 may be integrally formed or separate pieces formed separately.

The resilient member 154 provides a force to the impact block 152 that brings it closer to the anvil 153. In the present embodiment, the elastic member 154 is a coil spring.

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

The transmission mechanism 14 is provided between the motor 12 and the impact mechanism 15 for effecting transmission of power between the motor shaft 121 and the spindle 151. In this embodiment, the transmission 14 employs planetary gear reduction. Since the principle of operation of planetary gear reduction and the reduction produced by such a transmission are well known to those skilled in the art, a detailed description is omitted here for the sake of brevity.

As shown in fig. 1-3, the motor 12 includes stator windings 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, W that are electronically commutated. In some embodiments, a star connection is used between three-phase stator windings U, V, W, and in other embodiments, an angular connection is used between three-phase stator windings U, V, W. However, it must be understood that other types of brushless motors are also within the scope of the present disclosure. Brushless motors may include fewer or more than three phases.

The impact screw 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, W of the motor 12 for delivering current from the battery pack 30 to the stator windings U, V, W to drive the motor 12 to rotate. In one embodiment, the driving circuit 171 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, 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 a stator winding U, V, W of the motor 12. The switching elements Q1-Q6 receive control signals from the controller 17 to change the respective conductive states, thereby changing the current applied by the battery pack 30 to the stator windings U, V, 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 (FIELD EFFECT transistors, FETs), bipolar junction transistors (Bipolar Junction Transistor, BJTs), insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBTs), etc.). It will be appreciated that the switching element may be any other type of solid state switch, such as an Insulated Gate Bipolar Transistor (IGBT), a Bipolar Junction Transistor (BJT), etc.

In the present embodiment, the controller 17 is used to control the motor 12. The controller 17 is disposed on a control circuit board including a printed circuit board (Printed Circuit Board, PCB) and a flexible circuit board (Flexible Printed Circuit, FPC). The controller 17 employs a dedicated control chip, e.g., a single-chip microcomputer, a micro-control module (Microcontroller Unit, MCU). The controller 17 controls the on or off state of the switching elements in the driving circuit 171 specifically by a 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 (Pulse Width Modulation, PWM) signal. It should be noted that the control chip may be integrated into the controller 17, or may be provided independently of the controller 17, and the present embodiment is not limited as to the structural relationship between the driving chip and the controller 17.

The impact screw 100 further includes a power switch 16 and a switching section 163. The power switch 16 is provided on the grip portion 113 for operation by a user. The power switch 16 is used to control the energized state of the motor 12. The switching part 163 is provided at an upper side of the main switch 16, and the switching part 163 is configured to be operated to set a rotation direction of the motor 12 to a forward rotation direction in which a fastener is fastened or screwed in or a reverse rotation direction in which the fastener is unscrewed or unscrewed.

In the present embodiment, the power switch 16 is a travel switch, wherein the travel switch includes an operating member 161 and a slide rheostat 162 for operation. The power switch 16 can also regulate the rotational speed of the motor 12. The rotational speed of the motor 12 is adjusted according to the trigger stroke of the operating member 161. The trigger stroke of the operating member 161 is different, and the signal output from the slide rheostat 162 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, which is positively correlated with the rotational speed of the motor 12. When the trigger stroke of the trigger switch is small, the duty ratio of the PWM signal is also small, and at this time, the rotation speed of the motor 12 is also small.

In some embodiments, the impact screw driver 100 stores a mapping relationship between the trigger stroke of the operating member 161 and the PWM signal, which may be linear or non-linear, which is not limited by the embodiment of the present application.

The impact screw 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 rotation speed of the motor 12 to a first rotation speed, limit the rotation speed of the motor 12 to a non-driving rotation speed in response to the operation state of the motor 12 reaching a first limit condition, operate at a second rotation speed and drive the output shaft 131 to output torque in response to the rotation speed of the motor 12 being the non-driving rotation speed, the second rotation speed being smaller than the first rotation speed, the non-driving rotation speed being smaller than the second rotation speed. It is to be noted that the maximum output rotation speed of the motor 12 in the "maximum output rotation speed of the motor 12 is the first rotation speed" is the maximum speed output by the motor 12 when the trigger stroke of the operating member 161 of the power switch 16 is triggered to the limit stroke in the first control mode. The non-drive speed of the motor is such that when the motor is running at a non-drive speed, the output shaft 131 is not able to drive the fastener, which includes the motor 12 being shut down, i.e. at 0rpm, and the motor being limited to a speed near shut down such that it is not able to drive the fastener. The motor 12 may be operated at a second rotational speed, which may include automatically restarting the motor at the second rotational speed after the motor has been shut down, i.e., at 0rpm, or automatically operating at the second rotational speed after the motor has been limited to a speed near shutdown. In this embodiment, after limiting the output of the motor 12, the motor 12 is operated at the second rotational speed, and the two-stage operation is performed continuously or at short intervals. In some embodiments, the two phases are separated by less than or equal to 0.4s. Meanwhile, the starting signal is not required to be given again by the user between the two stages, namely, the user does not need to give a stop signal before giving the starting signal, or the user does not need to change the operation action.

In this embodiment, the operating condition of the motor 12 reaching the first limit condition includes the motor 12 driving the output shaft 131 to move in place in a preset condition after determining that the fastener operated by the output shaft 131 is in the first set condition based on the output shaft load.

The motor 12 driving the output shaft 131 to move in place in a preset condition includes at least one of a number of rotations of the motor 12 driving the output shaft 131 reaching a preset number of rotations, or a rotation time of the motor 12 driving the output shaft 131 reaching a preset time, or an axial displacement of the output shaft 131 reaching a preset displacement. The running state of the motor 12 reaches the first limiting condition, and the motor 12 is controlled to stop or close to stop and then automatically start at a low speed, so that a user can accurately control the stop position of the screw 50, and the success rate of the screw 50 being leveled with a target workpiece is improved. Compared with the control logic for directly stopping after a certain state is identified in the related art, the control scheme of the application is restarted at a low speed after stopping, can be suitable for more working conditions, has simpler identification conditions and has high control robustness.

Upon entering the first control mode, the maximum value of the output rotation speed of the motor 12 is limited to 70% or less of the maximum rotation speed of the motor 12, that is, the first rotation speed is 70% or less of the maximum rotation speed of the motor 12. In some embodiments, the first rotational speed is less than or equal to 60% of the maximum rotational speed of the motor 12. At this time, the stroke of the operating member 161 of the power switch 16 corresponds to the output rotation speed of the motor 12. In some embodiments, the motor 12 is started at a second rotational speed that is less than or equal to 50% of the maximum rotational speed of the motor 12 and is maintained at the first rotational speed to drive the output shaft 131 to output torque. In some embodiments, the second rotational speed is less than or equal to 40% of the maximum rotational speed of the motor 12. In some embodiments, the second rotational speed is less than or equal to 30% of the maximum rotational speed of the motor 12. In some embodiments, the second rotational speed is less than or equal to 20% of the maximum rotational speed of the motor 12. In some embodiments, the second rotational speed is less than or equal to 10% of the maximum rotational speed of the motor 12. In some embodiments, the second rotational speed is equal to 5% of the maximum rotational speed of the motor 12. At low start-up, the motor 12 is controlled to operate at a constant speed at the second rotational speed, which is more advantageous for the user to determine whether the screws 50 are flush.

As one example, fasteners are exemplified as screws 50, and target workpieces are exemplified as plasterboard 41 and metal board 42. As shown in fig. 4, a schematic view of a process of fastening a gypsum board 41 with a material board (e.g., a metal board 42) having a higher hardness than the gypsum board 41 using screws 50 is shown. As shown in fig. 5, a schematic diagram of the process current (I) and the time (T) of fastening the gypsum board 41 to the metal board 42 using the screw 50 is shown. Screw 50 includes a screw head 51, a threaded portion 52, and a piercing portion 53. The process of fastening the plasterboard 41 to the metal plate 42 using the screw 50 is generally divided into three stages, wherein the first stage is the P1 stage, and the screw part 52 and the piercing part 53 enter the stage where the plaster-to-piercing part 53 contacts the metal plate 42 (e.g., iron plate). The load on the output shaft 131 at this stage gradually increases as the depth of the screw portion 52 into the gypsum board 41, and the output current of the motor 12 gradually increases. The output rotational speed is controlled in accordance with a fixed duty cycle set by the voltage of the motor 12, at which stage the output rotational speed of the motor 12 is gradually reduced. The second stage is a P2 stage, in which the piercing portion 53 pierces through the metal plate 42 (e.g., iron plate). Since the metal plate 42 has a hardness greater than that of the gypsum board 41, the output shaft 131 is subjected to the greatest load, even abrupt, at the point in time when the penetrating portion 53 penetrates the metal plate 42. The output current of the motor 12 is at a maximum at this stage and the current decreases after the piercing portion 53 pierces the metal plate 42. The third stage is the P3 stage, where the screws 50 fasten the plasterboard 41 and the metal sheet 42 in place. Since the contact length of the metal plate 42 with the plasterboard 41 and the screw part 52 is nearly constant at this stage, until the top of the screw head 51 is flush with the plasterboard 41. Therefore, the load applied to the output shaft 131 is not substantially changed or fluctuates in magnitude during the gradual screwing. The output current of the motor 12 will first drop from the maximum value of the second phase P2.

In this embodiment, after the controller 17 enters the first control mode, the motor 12 is controlled to drive the output shaft 131 to rotate at a speed less than or equal to the first rotation 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 (e.g. iron plate) according to the current related parameter of the motor 12, the motor 12 drives the output shaft 131 to rotate for a fixed number of turns, and the controller 17 sends a stop signal to the motor 12, so that the output shaft 131 cannot drive the screw 50 to rotate. The rotation fixed number of turns of the output shaft 131 is calibrated in advance or corresponds to the rotation number of turns of the output shaft 131 according to the current related parameter of the motor 12 through a table look-up method. The controller 17 then controls the motor 12 to automatically start and output torque at the second rotational speed, and controls the motor to stop when the user outputs a stop signal. In the present embodiment, after the motor 12 is automatically started at the second rotation speed, the constant-speed operation is maintained, that is, the speed at which the motor 12 operates is not affected by the trigger stroke of the operating member 161 of the power switch 16. In some embodiments, after the motor 12 is automatically started at the second rotation speed, the speed of the motor 12 may 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 rotation speed.

Since the load of the output shaft 131 is substantially unchanged after the screw 50 is pierced through the metal plate 42, the user can precisely control the stop position of the screw 50 by using the output of the output shaft 131 having a low speed and a constant speed, and the success rate of the screw 50 being flush with the target workpiece can be improved. Compared with the control logic for directly stopping after a certain state is identified in the related art, the control scheme of the application is restarted at a low speed after stopping, can be suitable for more working conditions, has simpler identification conditions and has high control robustness.

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

In this embodiment, the controller 17 sends a stop signal to the motor 12 and the motor 12 employs a quick brake (e.g., a three-phase short), i.e., the output shaft 131 does not substantially rotate the fastener more than one revolution from the time the stop signal is sent to the controller 17 until the rotational speed of the motor 12 is 0 or near 0. Avoiding the influence of the rotation speed reduction process on the screwing-in screw 50.

In the present embodiment, the number of rotations of the output shaft 131 driven by the motor 12 is characterized by the phase change information of the motor 12. The commutation information for the motor 12 includes at least one of a commutation start point, a commutation end point, or a time period required to complete each commutation. When the duty ratio of the driving signal of the motor 12 is fixed, the greater the load of the output shaft 131, the smaller the rotation angle of the output shaft 131 is made by the impact force each time an impact occurs. And 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 commutation of the motor 12 is related to the number of rotations of the drive shaft of the motor 12, so that the parameters of the commutation of the motor 12 can characterize the number of rotations of the output shaft 131 or the angle of rotation of the output shaft 131.

Taking the three-phase brushless motor 12 in this embodiment as an example, the driving circuit includes six driving states, and the current flow direction can be controlled by opening different upper bridge arm switch element combinations and lower bridge arm switch element combinations, so as to generate magnetic fields in different directions, and enable the permanent magnet rotor to rotate to a designated position. Switching the drive circuit from one drive state to another drive state causes the motor 12 to perform a commutation. The upper bridge arm and the lower bridge arm are respectively provided with three switching elements, and six combinations are adopted, so that the motor 12 can rotate for one electrical cycle after six-step phase change every 60 degrees. It should be explained that one electrical cycle may not correspond to one complete mechanical rotation cycle of the rotor. The number of electrical cycles to be repeated to complete a mechanical turn depends on the number of pole pairs of the rotor. In commutation detection of the motor 12, in some embodiments, hall elements are used to detect the magnetic field of the rotor. Commutation information of the motor 12 is detected by hall sensors. 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 emf, the waveform change of the back emf voltage signal for each phase indicates commutation of the motor 12. Since the detection working principle of commutation of the motor 12 using the sensor and the sensorless is well disclosed to those skilled in the art, a detailed description is omitted herein for the sake of brevity of description.

When detecting the number of rotations of the output shaft 131, an example is to detect the start point of commutation of the motor 12. When the commutation start point of the commutation of the motor 12 is detected every time, the number of commutation times is +1, and the total number of commutation times is accumulated. The controller 17 stores therein a correspondence relationship between the total number of commutation 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 commutation reaches a preset number of rotations, the motor 12 is controlled to stop.

In some embodiments, after the controller 17 determines that the screw 50 is threaded through the metal plate 42 (e.g., iron plate) according to the current-related parameter of the motor 12, the controller 17 sends a stop signal to the motor 12 after the motor 12 drives the rotation of the output shaft 131 for a preset time so that the output shaft 131 cannot rotate while driving the screw 50. The rotation preset time of the output shaft 131 is calibrated in advance or corresponds to the rotation time of the output shaft 131 according to the current related parameter of the motor 12 by a table look-up method. The rotational time of the output shaft 131 can be characterized using the operating time of the motor 12, among other things. The timing is performed by setting a timer or a timing module in the controller 17.

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 parameter of the motor 12, the controller 17 sends a stop signal to the motor 12 after the axial displacement of the output shaft 131 driven by the motor 12 reaches a preset displacement amount, so that the output shaft 131 cannot rotate when the screw 50 is driven. The preset displacement amount of the axial displacement of the output shaft 131 is calibrated in advance or corresponds to the axial displacement of the output shaft 131 according to the current related parameter of the motor 12 through a table look-up method. Wherein the axial displacement of the output shaft 131 can be measured using a position sensor.

In the present embodiment, the control mechanism 17a further includes a first detecting component 181 for detecting a preset condition parameter of the output shaft 131. Such as 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 emf voltage.

The fastener is determined to be in the first setting by comparing the load parameter of the output shaft 131 with the first threshold. In this embodiment, the first setting of the fastener is the screw 50 driving through the metal plate 42. The first threshold is a value calibrated in advance.

In the present embodiment, the second detecting component 182 is further included for detecting a load parameter of the output shaft 131. In the present embodiment, the load parameter of the output shaft 131 includes a motor 12 current-related parameter. It should be noted that the parameters related to the current of the motor 12 include the current of the motor 12 and the calculated parameters of 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.

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

The rotation speed of the motor 12 is detected by a magnetic ring, magnetic steel or photoelectric encoder, an inductance, a Hall sensor or a photoelectric sensor.

In some embodiments, the load parameter of the output shaft 131 is characterized using the rotational parameter of the output shaft 131. The rotation parameter of the output shaft 131 includes at least one parameter of a rotation speed of the output shaft 131, a rotation angle of the output shaft 131, and a rotation acceleration of the output shaft 131. The second detecting assembly 182 is used for detecting a rotation parameter of the output shaft 131. The second detection component 182 includes a position sensor, which may be a photodiode sensor, a magnetic sensor, or a potentiometer. The second detection component 182 may also be a rotation sensor, in particular a gyroscopic sensor. The gyroscope sensor may be a single, two or three axis microelectromechanical system (MEMS) sensor or a rotational sensor. When the parameters detected by the first detecting component 181 and the second detecting component 182 are the same, the first detecting component 181 and the second detecting component 182 may be combined.

When the motor 12 receives a stop command in the first control mode of the impact screw 100, the controller 17 controls the motor 12 to stop. When the motor 12 receives the start signal again, it is determined that a 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, and the impacting screw driver 100 enters the second control mode. In the second control mode, however, the controller 17 limits the output of the motor and does not perform the control of the first control mode. This allows the motor 12 to operate at a low speed when the motor 12 is restarted for a short period of time after exiting the low speed mode. In the present embodiment, in the second control mode, the maximum value of the output rotation speed of the motor 12 is 70% or less of the maximum output rotation speed of the motor 12, and the stroke of the power switch 16 corresponds to the output rotation speed of the motor 12. Thus, when the user does not determine whether the fastener is in place, the motor 12 will start at a lower speed even if the machine is stopped to check the status of the fastener, and the motor 12 is restarted in a short period of time. When t1 is greater than the first time parameter t, the second control mode is not entered, and corresponding control logic is provided according to the current setting of the impacting screw driver 100.

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, 1.0s.

In this embodiment, the impact screw 100 includes a mode selection portion, and the impact screw 100 includes a first gear mode, a second gear mode, or more other modes, which are set for different target workpieces, or fasteners, or for a particular operating condition. The first control mode and the second control mode both belong to partial control modes under the first gear mode. The activation condition of the first control mode includes first selecting the first gear mode in which the first control mode is activated to be entered when the displacement stroke of the operating member 161 of the power switch 16 satisfies the preset stroke. In the present embodiment, the displacement stroke of the operating member 161 including the power switch 16 is greater than 50% of the total stroke, and is activated into the first control mode.

In some embodiments, the first control mode and the second control mode are also used for the second gear mode. In some embodiments, the first control mode and the second control mode are also used for other modes. The foregoing does not affect the essence of the application.

As shown in fig. 6, the embodiment further discloses a control method of the impact tool, which specifically includes:

And S110, controlling the maximum output rotating speed of the motor 12 to be the first rotating speed.

S120 is to determine that the operating state of the motor 12 reaches the first limit condition.

And S130, limiting the rotation speed of the motor to a non-driving rotation speed so that the output shaft 131 cannot drive the fastener.

The motor 12 operates at a second rotational speed, which is less than the first rotational speed, and drives the output shaft 131 to output torque, and the non-driving rotational speed is less than the second rotational speed S140.

The use of low speed rotation to control the output of the output shaft 131 allows the user to precisely control the stop position of the screw 50, improving the success rate of the screw 50 being flush with the target workpiece. Compared with the control logic for directly stopping after a certain state is identified in the related art, the control scheme of the application is restarted at a low speed after stopping, can be suitable for more working conditions, has simpler identification conditions and has high control robustness.

As shown in fig. 7, the present embodiment further discloses another method for controlling an impact tool, which specifically includes:

S210, the first gear mode is selected by switching the impact screw driver 100.

S220, judging that the displacement stroke of the operating member 161 of the power switch 16 meets the preset stroke, if yes, executing S240, and if not, executing S230.

S230, exiting the first gear mode.

S240, activating a first gear mode, and controlling the motor 12 to operate at a speed less than or equal to a first rotating speed.

Upon entering the first control mode, the maximum value of the output rotation speed of the motor 12 is limited to 70% or less of the maximum rotation 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 rotation speed of the motor 12.

S250, determining that the screw 50 penetrates through the metal plate 42 according to the current related parameters of the motor 12, if yes, executing S260, and if not, executing S240.

The load parameter of the output shaft 131 is characterized according to the current-related parameter of the motor 12, and the screw 50 is determined to pierce the metal plate 42 by comparing the load parameter of the output shaft 131 with a first threshold value. Meanwhile, the load parameter of the output shaft 131 can be represented according to at least one of the related parameters of the rotation speed of the motor 12, 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.

S260, the motor 12 drives the output shaft 131 to rotate for a fixed number of turns.

The number of rotation fixed turns of the output shaft 131 is calibrated in advance or corresponds to the number of rotation turns of the output shaft 131 according to the current-related parameter of the motor 12 by a table look-up method. By using a 25mm long screw 50, a10 mm thick plasterboard 41, the test screw 50 was screwed into a thickness of about 15mm, and a standard threshold was determined according to the number of threads of the screw 50 within 15mm, and then adjusted by the hand feeling of the actual operation.

In some embodiments, the motor 12 drives the rotation time of the output shaft 131 to a preset time, or the axial displacement amount of the output shaft 131 reaches a preset displacement amount. The preset time and the preset displacement are also the rotation time of the output shaft 131 and the displacement of the output shaft 131, which are calibrated in advance or correspond to the current related parameters of the motor 12 through a table look-up method.

S270 is to send a stop signal to the motor 12 so that the output shaft 131 cannot drive the screw 50 to rotate.

The controller 17 sends a stop signal to the motor 12 and the motor 12 applies a quick brake, i.e. the output shaft 131 will not substantially rotate the screw 50 more than one revolution from the time the stop signal is sent to the controller 17 until the rotational speed of the motor 12 is 0 or close to 0. Avoiding the influence of the rotation speed reduction process on the screwing-in screw 50.

And S280, controlling the motor 12 to automatically work at the second rotating speed and outputting torque. Wherein the second rotational speed is less than the first rotational speed.

In this embodiment, the motor 12 is maintained at constant speed after being automatically started at the second rotational speed. In some embodiments, after the motor 12 is automatically started at the second rotation speed, the speed of the motor 12 may 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 rotation speed.

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

S290, the user outputs a stop signal, if yes, S291 is executed, and if no, S280 is executed.

S291, ending.

As shown in fig. 8, the present embodiment further discloses a third method for controlling an impact tool, which specifically includes:

S210, the first gear mode is selected by switching the impact screw driver 100.

S230, exiting the first gear mode.

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

S291, stopping the impact screw 100.

S300, the motor 12 receives the start signal again.

S310, judging 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 smaller than or equal to the first time parameter t, if yes, executing S320, and if not, executing S330.

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

The controller 17 limits the output rotation speed of the motor and does not perform the control of the first control mode S320. Upon receiving the shutdown instruction, S291 is returned.

S330, not entering the second control mode, corresponding to the corresponding control logic according to the current setting of the impacting screw driver 100.

As some embodiments of the present application, the above disclosed embodiments are also applicable to other power tools that use a motor drive, output a torque force from an output shaft, and do not have an impact assembly. For example, the power tool may be a screwdriver, an electric drill, a wrench, or the like. The present application is not limited in the type of power tool. It is within the scope of the present application that the power tool can employ the above disclosed technical solution.

The foregoing has shown and described the basic principles, principal features and advantages of the application. It will be appreciated by persons skilled in the art that the above embodiments are not intended to limit the application in any way, and that all technical solutions obtained by means of equivalent substitutions or equivalent transformations fall within the scope of the 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, 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 is characterized in that the operating state of the motor reaches the first limiting condition, including: after determining that the fastener operated by the output shaft is in a first set state according to the load parameters of the output shaft, the motor drives the output shaft to move into place according to preset conditions.

3. The impact tool according to claim 2 is 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 reach a preset number of rotations, or the rotation time driven by the motor to reach a preset time, or the axial displacement of the output shaft reaches at least one of the preset displacements.

4 . The impact tool according to claim 2 , wherein the load parameter of the output shaft comprises 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 , wherein the load parameter of the output shaft comprises 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 , wherein the number of rotations of the output shaft driven by the motor is represented by 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 is 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 a first time parameter, and the impact tool enters the second control mode.

9 . The impact tool according to claim 8 , wherein 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 is characterized in that the impact tool comprises a power switch for receiving a user's power-on command and a power-off command, and 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 , wherein the power switch comprises a travel switch, and when the displacement travel of the travel switch satisfies a preset travel, the controller enters the first control mode.

12. An impact tool comprising:

a motor including a drive shaft that rotates about a first axis;

A controller, used for controlling the motor;

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;

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 control method for an impact tool, characterized in that the impact tool comprises:

a motor including a drive shaft that rotates about a first axis;

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.