Impact tool

Abstract

The invention discloses an impact tool. The impact tool includes: a motor including a drive shaft rotating about a first axis; the output shaft is used for outputting torque outwards; the impact mechanism is used for applying impact force to the output shaft; the impact mechanism comprises an impact block driven by the driving shaft and a hammer anvil receiving impact from the impact block; the output shaft is connected to the hammer anvil; the controller is used for controlling the motor; wherein the controller is configured as follows: when the impact tool is in a low-speed mode and the impact mechanism is detected to apply impact force to the output shaft, the motor periodically executes the following steps: determining that the impact mechanism generates impact for a preset number of times, controlling the motor to stop for a preset time and then starting; the invention provides an impact tool capable of providing low-speed impact.

Description

Technical Field

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

[0002] Impact tools refer to tools that can output rotational motion at a certain impact frequency. Common impact tools include impact wrenches, impact screwdrivers, impact drills, etc. Impact wrenches are usually used to tighten bolts and nuts, impact screwdrivers are usually used to loosen or tighten screws, and impact drills are usually used to punch holes.

[0003] In order to output a rotational motion with a certain impact frequency, the impact tool usually includes an output component for outputting a rotational force and an impact mechanism for periodically impacting the output component. In related technical products, when an impact screwdriver loosens a thin screw, the impact screwdriver rotates too fast after the trigger is pressed. If the screw is in a fully tightened state at this time, the screw head speed is too fast, which will cause damage to the screw operating surface. When the impact screwdriver tightens a thin screw, sometimes the screw is not completely flush with the operating surface, and it is necessary to continue to operate to completely drive the screw in. At this time, the impact screwdriver impacts too fast, which will cause damage to the operating surface.

[0004] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0005] 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 can provide low-speed impact.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] An impact tool comprising:

[0008] a motor including a drive shaft that rotates about a first axis;

[0009] Output shaft, used for outputting torque externally;

[0010] 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;

[0011] A controller, used for controlling the motor;

[0012] Wherein, the controller is configured as:

[0013] When the impact tool is in low-speed mode, when it is detected that the impact mechanism applies an impact force to the output shaft, the motor periodically executes: determining that the impact mechanism has impacted a preset number of times, and controlling the motor to stop for a preset time and then start.

[0014] In some embodiments, the impact tool further includes a trigger switch for adjusting the rotation speed of the motor, and the controller is configured to: determine that the trigger stroke is within a preset stroke range according to a stroke signal of the trigger switch, and determine that the impact tool is in low-speed mode.

[0015] In some embodiments, the controller is specifically configured to:

[0016] When the trigger stroke exceeds the preset stroke range, it is determined that the impact tool is in a non-low-speed mode, and the motor is controlled to continuously rotate and output, so that the impact mechanism generates periodic impacts on the output shaft.

[0017] In some embodiments, the controller is specifically configured to:

[0018] When the trigger stroke exceeds the preset stroke range, it is determined that the impact tool is in a non-low-speed mode, and a required duty cycle of the motor drive signal of the motor is determined based on the trigger stroke. The motor drive signal is output to the motor to control the motor to continuously rotate and output at the required duty cycle.

[0019] In some embodiments, the impact tool includes a battery pack for powering the motor, and the controller is configured to:

[0020] After the motor stops for a preset time, a target duty cycle of a motor driving signal of the motor is determined based on the voltage of the battery pack, and the motor is controlled to start running with the target duty cycle.

[0021] In some embodiments, the target duty cycle is less than or equal to 40%.

[0022] In some embodiments, the controller is configured to: obtain a motor commutation state, and determine the number of impacts based on the motor commutation state.

[0023] In some embodiments, the controller is specifically configured to: control the windings of the motor to be short-circuited to brake the motor, and start the motor after the preset time.

[0024] In some embodiments, the preset number of times includes once.

[0025] In some embodiments, the preset time is positively correlated with the trigger travel.

[0026] An impact tool comprising:

[0027] a motor including a drive shaft that rotates about a first axis;

[0028] Output shaft, used for outputting torque externally;

[0029] 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;

[0030] A controller, used for controlling the motor;

[0031] Wherein, the controller is configured as:

[0032] When the impact tool is in low-speed mode, when the load parameter exceeds a preset parameter threshold, the motor periodically executes: determining that the impact mechanism meets the conditions for a preset number of impacts, and controlling the motor to stop for a preset time and then start.

[0033] In some embodiments, the controller is configured to:

[0034] According to the fact that the motor does not commutate within a preset commutation time, it is determined that the load parameter exceeds a preset parameter threshold.

[0035] In some embodiments, the controller is configured to:

[0036] According to a phase error occurring in the motor, it is determined that the load parameter exceeds a preset parameter threshold.

[0037] In some embodiments, the controller is configured to:

[0038] The commutation state of the motor is acquired, and based on whether the commutation state of the motor satisfies a preset commutation threshold, it is determined that the impact mechanism has impacted a preset number of times.

[0039] The benefit of the present application is that when the impact tool is in low-speed mode, when it is detected that the impact mechanism applies an impact force to the output shaft, the motor periodically executes: determining that the impact mechanism has a preset number of impacts, and controlling the motor to stop for a preset time before starting. Therefore, through the cycle control of the preset number of impacts plus the preset stop time, the impact tool can produce continuous low-speed impacts with controllable impact frequency, preventing the impact tool from damaging the operating surface due to excessive impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of an impact tool according to an embodiment of the present application;

[0041] Figure 2 yes Figure 1 A cross-sectional view of the impact tool;

[0042] Figure 3 is a circuit diagram of an impact tool according to an embodiment of the present application;

[0043] Figure 4 A control flow chart of an impact tool according to an embodiment of the present application;

[0044] Figure 5 A control flow chart of an impact tool according to another embodiment of the present application;

[0045] Figure 6 A control flow chart of an impact tool according to another embodiment of the present application;

[0046] Figure 7 A control flow chart of an impact tool according to another embodiment of the present application;

[0047] Figure 8 A control flow chart of an impact tool according to another embodiment of the present application;

[0048] Fig. 9 A control flow chart of an impact tool according to another embodiment of the present application;

[0049] Fig.10 A control flow chart of an impact tool according to another embodiment of the present application;

[0050] Fig.11 This is a control flow chart of an impact tool according to another embodiment of the present application. DETAILED DESCRIPTION

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] In the present 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, 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 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).

[0056] 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.

[0057] 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.

[0058] 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.

[0059] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0060] 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.).

[0061] In order to clearly illustrate the technical solution of the present application, the upper side, lower side, left side, and right side are defined in the drawings of the specification.

[0062] 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.

[0063] 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 can specifically be a battery pack. 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.

[0064] 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.

[0065] 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.

[0066] The output shaft 131 is used to output torque to operate the fastener, and the output shaft 131 rotates around the output axis. In this embodiment, the output axis is the second axis 102. In this embodiment, the first axis 101 coincides with the second axis 102. In other alternative embodiments, the second axis 102 is set at a certain angle to the first axis 101. In other alternative embodiments, the first axis 101 and the second axis 102 are parallel to each other but do not coincide.

[0067] 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.

[0068] 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. A pair of first ball grooves with openings facing forward and extending backward in the front-to-back direction are also provided on the front end surface of the impact block 152. A pair of second ball grooves are also formed on the outer surface of the main shaft 151. The impact mechanism 15 also includes a rolling ball. The rolling ball spans the first ball groove and the second ball groove, thereby connecting the impact block 152 to the main shaft 151. In this embodiment, the rolling ball is a steel ball.

[0069] 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 power supply device 30.

[0070] 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.

[0071] During operation, when the impact screwdriver 100 is unloaded, the impact mechanism 15 does not impact, and the impact mechanism 15 plays a transmission role, transmitting the rotation of the motor 12 to the output shaft 131. When a load is applied to the impact tool 100, the rotation of the output shaft 131 is blocked. Due to the different load sizes, the output shaft 131 may reduce the speed or completely stop rotating. When the output shaft 131 completely stops rotating, the anvil 153 also stops rotating. Due to the circumferential limiting effect of the anvil 153 on the impact block 152, the impact block 152 also stops rotating, but the spindle 151 continues to rotate, which causes the rolling ball to be squeezed and move along the ball track, thereby driving the impact block 152 to produce a backward displacement along the spindle axis. At the same time, the elastic element 154 is squeezed until the anvil 153 is completely disengaged from the impact block 152. At this time, the spindle 151 drives the impact block 152 to rotate at a certain speed, and the elastic element 154 rebounds axially. When the impact block 152 rotates to contact the anvil 153, an impact force is applied to the anvil 153. Under the action of this impact force, the output shaft 131 continues to rotate a certain angle to overcome the load, and then the output shaft 131 stops again, and the above process is repeated. Since the impact frequency is large enough, a relatively continuous impact force is generated on the output shaft 131, so that the working accessory continues to work.

[0072] like Figure 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 connected in a star connection, and in other embodiments, the three-phase stator windings U, V, and W are connected in an angle connection. 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.

[0073] like Figure 1-Figure 3As shown, the impact screwdriver 100 includes a control mechanism. The control mechanism 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 switch elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate terminal of each switch element is electrically connected to the controller 17 for receiving a control signal from the controller 17. The drain or source of each switch 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.

[0074] 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.

[0075] 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. In this embodiment, the switching portion 163 is a switching switch.

[0076] In this embodiment, the power switch 16 is a trigger switch, wherein the trigger switch includes a speed adjustment portion 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 speed adjustment portion 161. The signal output by the sliding rheostat 162 is different when the trigger stroke of the speed adjustment portion 161 is different.

[0077] The trigger stroke of the speed adjustment unit 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. The trigger stroke of the speed adjustment unit 161 is the trigger stroke of the trigger switch. 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.

[0078] In some embodiments, the impact screwdriver 100 stores a mapping relationship between the trigger stroke of the speed adjustment unit 161 and the PWM signal. The mapping relationship may be linear or nonlinear, which is not limited in the embodiments of the present application.

[0079] In some embodiments, the impact screwdriver 100 further includes a detection unit 18, which is used to detect motor parameters, including at least one of the motor voltage and the motor current. The input end of the detection unit 18 is electrically connected to the motor 12, and the output end of the detection unit 18 is electrically connected to the controller 17, so that the controller 17 can obtain the motor parameters detected by the detection unit 18. In some embodiments, the detection unit 18 is used to detect the current of the motor, and the detection unit 18 includes a current sensing resistor, a Hall current sensor, or a mosfet (metal oxide semiconductor field effect transistor) on-resistance. In some embodiments, the detection unit 18 is used to detect the voltage of the motor, and the detection unit 18 includes one or more of an electromagnetic voltage transformer, a Hall voltage sensor, a voltage divider voltage sensor, an optical fiber voltage sensor, and a resistor divider.

[0080] Considering that when the screw is in a fully tightened state or the screw is not completely flush with the operating surface, the impact of the screwdriver 100 is too fast and may cause damage to the operating surface. In the related art, each time the impact mechanism 15 of the impact tool impacts, the load value of the impact mechanism 15 changes. The load value change process is generally as follows: before the impact mechanism 15 impacts, the load value of the impact mechanism 15 continues to increase, and when the load value of the impact mechanism 15 reaches a threshold, the impact mechanism 15 impacts. After the impact mechanism 15 impacts, the load value of the impact mechanism 15 decreases immediately. After the impact mechanism 15 impacts once, when the motor continues to rotate, the impact of the impact mechanism 15 will continue to occur, which results in a short interval between two impacts and a short duration of a single impact.

[0081] When analyzing the impact process of the impact tool in the related art step by step, the applicant found that in the first stage, when the load on the impact mechanism 15 continues to increase, in order to ensure that the motor 12 will not be reversely driven by the load at the motor output end, that is, the torque value output by the motor 12 is greater than the load value of the components driven by the motor 12, it is necessary to increase the speed of the motor 12 to output a suitable torque. It should be noted that if the motor 12 is reversely driven by the load at the motor output end, during the sensorless control process of the motor 12, the phase or back electromotive force of the motor 12 and other parameters for detecting the motor rotor position will become abnormal. At the same time, if severe reverse driving occurs, there is a possibility of damaging the motor 12. If the motor speed is increased to match the load value, low-speed control will not be achieved.

[0082] In the second stage, after the impact mechanism 15 impacts, the load value of the impact mechanism 15 decreases immediately. At this time, the motor 12 needs to decelerate as the load value changes. However, due to the short interval between the two impacts, the motor 12 decelerates too quickly, which will cause the next impact to occur, and the load needs to accelerate faster in the rising stage. If the motor 12 does not decelerate, low-speed control cannot be achieved.

[0083] In one embodiment of the present application, the controller 17 is configured as follows: when the impact tool is in low-speed mode, when it is detected that the impact mechanism 15 applies an impact force to the output shaft 131, the motor 12 periodically executes: determining that the impact mechanism 15 has a preset number of impacts, and controlling the motor 12 to stop for a preset time and then start. Among them, the low-speed mode is a mode that characterizes the motor providing low-speed rotation. Through the cyclic control of the preset number of impacts plus the preset stop time, the impact screwdriver 100 can generate continuous and controllable low-speed impacts with a controllable impact frequency when the motor rotates at a low speed, thereby preventing the impact screwdriver 100 from damaging the operating surface due to excessive impact.

[0084] Since the motor 12 has a certain acceleration when it is started, after it is determined that the impact mechanism 15 has a preset number of impacts, the motor 12 is immediately controlled to stop and brake, and after stopping for a suitable preset time, the motor 12 is started again with a certain acceleration, so that the impact mechanism 15, such as the impact block 152, has a higher moment of inertia, so that the impact mechanism 15 generates a larger impact torque. At the same time, since there is a stop time between two impacts, the average speed of the output shaft 131 per unit time is also reduced, thereby realizing the low-speed control of the output state of the impact screwdriver 100.

[0085] In this embodiment, the motor 12 is started with a preset acceleration value. When the impact screwdriver 100 is unloaded, the controller 17 controls the motor 12 to be set to start with a first acceleration value, and the preset acceleration is greater than the first acceleration. The first acceleration and the preset acceleration are respectively pre-calibrated parameters and stored in the controller 17. When the trigger switch is activated, the controller 17 determines that the impact screwdriver 100 is unloaded, and the controller 17 sends a signal to the motor 12 to start with the first acceleration value. When the controller 17 determines that the impact screwdriver 100 is in low-speed mode, the controller 17 sends a signal to the motor 12 to start with the preset acceleration value. Optionally, other starting acceleration values ​​are stored in the controller 17 to correspond to different starting conditions of the impact screwdriver 100. The preset acceleration value can be the maximum acceleration value, or it can be a starting acceleration value greater than the first acceleration value but less than other conditions. The adaptability setting of the above specific values ​​does not limit the substantive content of this application.

[0086] In some embodiments, the controller 17 is configured to: determine that the trigger stroke is within a preset stroke range according to the stroke signal of the trigger switch, and determine that the impact tool is in low-speed mode. The stroke signal is a signal representing the trigger stroke size of the trigger switch, and the preset stroke range is the range of the trigger stroke when the impact tool is in low-speed mode. Therefore, it can be determined that the impact tool is in low-speed mode when the trigger stroke is within the preset stroke range.

[0087] In some embodiments, the controller 17 is specifically configured to: control the windings of the motor 12 to be short-circuited to brake the motor 12, and start the motor 12 at a preset acceleration after a preset time. The short-circuit braking of the motor 12 is achieved by using the induced electromotive force of the motor 12. When the rotor of the motor 12 rotates, an induced electromotive force is generated in the stator winding due to the change in the magnetic field. When the two windings of the motor 12 are short-circuited, the induced electromotive force will generate a certain current flowing through the winding, forming an electromagnetic braking force, which can offset the mechanical movement of the motor 12, thereby achieving a braking effect.

[0088] After the motor 12 is started at a preset acceleration and a preset number of impacts are made, the winding of the motor 12 is immediately controlled to be short-circuited to brake the motor 12, and then the motor 12 is started at a preset acceleration and a preset number of impacts are made, and this cycle is repeated so that the impact block in the tool has a higher moment of inertia, thereby generating a larger impact torque. At the same time, the subsequent rapid shutdown of the motor 12 enables the impact tool to run at a low speed, and the user can easily control the tool.

[0089] In some embodiments, the preset number of times includes one time, that is, the impact tool performs one impact, stops for a preset time, then performs another impact, and then stops for a preset time, so that the impact tool can run at a low speed.

[0090] In some embodiments, the preset time is positively correlated with the trigger stroke. The longer the preset time is, the longer the motor 12 is stopped. Therefore, when the trigger stroke is larger, the motor 12 is stopped for a longer time, and when the trigger stroke is smaller, the motor 12 is stopped for a shorter time. In a specific embodiment, the preset time includes 320ms. In other replaceable embodiments, the preset time includes 200ms. Optionally, the specific preset time is determined based on the mapping relationship between the trigger stroke and the preset time and the current trigger stroke. The embodiments of the present application do not specifically limit this. In some embodiments, the impact screwdriver 100 stores a mapping relationship between the trigger stroke and the preset time. The mapping relationship can be linear or nonlinear. The embodiments of the present application do not limit this.

[0091] In some embodiments, the controller 17 is configured to: when the motor 12 stops for a preset time, determine the target duty cycle of the motor drive signal of the motor 12 based on the voltage of the battery pack 30, and control the motor 12 to start running with the target duty cycle. In this embodiment, the voltage of the battery pack 30 is defined as Ua, and the voltage U of the motor 12 = Ua*duty cycle of the motor drive signal. Therefore, in order to ensure that U remains unchanged, the duty cycle of the motor drive signal can be adjusted according to the change of Ua. The target duty cycle is the duty cycle that the motor drive signal needs to achieve. The target duty cycle is inversely proportional to the voltage of the battery pack 30, so that when the voltage of the battery pack 30 is reduced, the voltage applied to the motor 12 remains unchanged, and the output power of the motor 12 remains basically unchanged, while the output torque is related to the output power, and the torque generated by the power remains almost unchanged. Therefore, as the power of the battery pack 30 is consumed, the output torque of the impact tool is relatively stable.

[0092] In some embodiments, the target duty cycle is less than or equal to 40%. In a specific embodiment, the target duty cycle is 30%. In another specific embodiment, the target duty cycle is 32%. In other alternative embodiments, the target duty cycle is 35%. The specific size of the target duty cycle can be set according to the specific structure and use requirements of the impact tool, and is not specifically limited here, as long as it is less than or equal to 40%, so that the impact tool can run at a low speed.

[0093] In some embodiments, the impact state of the impact mechanism 15 is determined by the current of the motor 12. Whether an impact occurs is determined by the change in current during impact. Optionally, the current can be detected by any one of a current-sensing resistor, a Hall current sensor, or a mosfet (metal oxide semiconductor field effect transistor) on-resistance. In other alternative embodiments, by detecting various physical signals when an impact occurs, such as electrical signals, audio signals, etc., judgment and collection are performed, and then feedback is given to the controller 17 to determine that the impact mechanism 15 begins to impact the output shaft 131. In some embodiments, the detection unit 18 determines the demagnetization time by detecting the bus voltage, and determines that the impact mechanism 15 begins to impact the output shaft 131 by the demagnetization time. For professionals and technicians in this field, it has been fully disclosed that the above method is used to determine that the impact mechanism 15 enters the impact, that is, the impact mechanism 15 begins to apply impact force to the output shaft 131. Therefore, the above does not limit the substantive content of the present invention.

[0094] In some embodiments, the controller 17 is configured to: obtain the motor commutation state, and determine the number of impacts based on the motor commutation state. In this embodiment, the motor commutation state includes the current number of commutations. When the current number of commutations is greater than the preset number of commutations threshold, it is determined that the impact mechanism 15 applies an impact force to the output shaft 131, generating an impact, and the number of impacts is increased by one, and the current number of commutations is restarted. The preset number of commutations threshold is related to the reduction ratio of the transmission mechanism 14, and the preset number of commutations threshold can be preset according to the reduction ratio of the transmission mechanism 14 of the current impact tool. The specific size of the preset number of commutations threshold is not specifically limited here.

[0095] In some embodiments, the current of the motor 12 can be sampled by any one of a current-sensing resistor, a Hall current sensor, or a mosfet (metal oxide semiconductor field effect transistor) on-resistance, and then the sampled current is amplified to form a waveform analog quantity, and then the analog quantity is converted into a digital quantity, and finally the rate of change of the digital quantity data is calculated, and it is determined whether the direction of the data change rate changes. When the direction of the data change rate changes, it is determined that the motor 12 has generated a phase change, and the current number of phase changes is increased by one. Other methods in the relevant technology can also be used to obtain the motor phase change state, and the specific method for obtaining the motor phase change state is not specifically limited here.

[0096] In some embodiments, the controller 17 is specifically configured as follows: when the trigger stroke exceeds the preset stroke range, it is determined that the impact tool is in a non-low-speed mode, and the motor 12 is controlled to continuously rotate and output, so that the impact mechanism 15 produces periodic impacts on the output shaft 131. Among them, since the preset stroke range is the range of the trigger stroke when the impact tool is in the low-speed mode, when the trigger stroke exceeds the preset stroke range, it means that the impact tool is in a non-low-speed mode and the speed needs to be increased. At this time, the motor 12 is controlled to continuously rotate and output. Compared with the cyclic control of the preset number of impacts in the low-speed mode plus the preset shutdown time, the impact speed is faster, which can enable the impact mechanism 15 to produce periodic large impacts on the output shaft 131.

[0097] In some embodiments, the controller 17 is specifically configured to: when the trigger stroke exceeds a preset stroke range, determine that the impact tool is in a non-low-speed mode, determine the required duty cycle of the motor drive signal of the motor 12 based on the trigger stroke, and output the motor drive signal to the motor 12 to control the motor 12 to continuously rotate and output at the required duty cycle.

[0098] Among them, the trigger stroke is positively correlated with the duty cycle of the drive signal of the motor 12, and the duty cycle of the drive signal is positively correlated with the rotational speed of the motor 12. In some embodiments, the impact screwdriver 100 stores a mapping relationship between the trigger stroke and the duty cycle of the drive signal of the motor 12. The mapping relationship can be linear or nonlinear, and the embodiments of the present application are not limited to this. The required duty cycle is the duty cycle of the drive signal of the motor 12 corresponding to the current trigger stroke. The larger the trigger stroke, the larger the required duty cycle and the faster the rotational speed of the motor 12. Therefore, the rotational speed of the motor 12 will be adjusted according to the trigger stroke at this time, so that the impact screwdriver 100 produces periodic and faster continuous impacts.

[0099] In summary, from the perspective of the entire control process of the impact tool, when the trigger stroke is within the preset stroke range and the impact tool is in low-speed mode, after detecting that an impact occurs, the impact tool can produce continuous low-speed impacts with controllable impact frequency through a preset number of impacts plus a preset stop time. When the trigger stroke exceeds the preset stroke range and is in non-low-speed mode, the speed of the motor 12 will be adjusted according to the trigger stroke, so that the impact screwdriver 100 can produce periodic and relatively fast continuous impacts. Therefore, the impact tool can operate stably and will not stall whether it is at a low speed or a high speed. It can produce slow impacts or fast impacts, and it can be fast or slow as you want. It will not stall even when it drops from high speed to extremely slow, and the user experience is good. In one embodiment of the present application, the controller 17 is configured as follows: when the impact tool is in low-speed mode, when the load parameter exceeds the preset parameter threshold, the motor 12 periodically executes: by determining that the impact mechanism 15 meets the conditions for the occurrence of a preset number of impacts, the motor 12 is controlled to stop for a preset time and then start. .

[0100] Among them, the preset parameter threshold includes the maximum value of the load parameter when the impact mechanism 15 of the impact tool is operating as a transmission. When the load parameter exceeds the preset parameter threshold, it means that the impact mechanism 15 should have an impact. However, in the related art, when the output speed of the motor 12 is relatively low, the rotation of the impact block 152 is easily blocked. At this time, according to different program settings, the motor 12 may start the stall protection and continue to shut down or increase the speed to increase the output of the motor 12, thereby causing the impact block 152 to break through the stall point. At this time, low-speed operation cannot be achieved.

[0101] In this embodiment, when the impact tool determines that the trigger stroke is within the preset stroke range according to the stroke signal of the trigger switch and determines that the impact tool is in low-speed mode, when the controller 17 determines that the load parameter exceeds the preset parameter threshold, the motor 12 is controlled to stop for a preset time and then start after determining that the impact mechanism 15 meets the conditions for a preset number of impacts. Among them, "determining that the impact mechanism 15 meets the conditions for a preset number of impacts" does not necessarily correspond to the impact mechanism 15 applying an impact force to the output shaft. Rather, it means that the pre-set conditional parameter that can characterize the number of impacts meets the preset value. At this time, the impact mechanism 15 may apply an impact force to the output shaft 131, or the impact mechanism 15 may not or continue to apply an impact force.

[0102] Since the motor 12 is controlled to start after stopping for a preset time, that is, after the motor 12 is stopped and braked and stopped for a suitable preset time, the motor 12 is started again with a certain acceleration, so that the impact mechanism 15, for example, the impact block 152 has a higher moment of inertia, so that the impact mechanism 15 generates a larger impact torque. Then, relative motion can occur between the impact block 152 and the hammer anvil 153. By cyclically controlling the preset start and stop times, the impact screwdriver 100 can generate continuous low-speed impacts with controllable impact frequency, preventing the impact screwdriver 100 from damaging the operating surface due to excessively fast impacts.

[0103] In this embodiment, the controller obtains the commutation state of the motor 12, and determines that the impact mechanism 15 has a preset number of impacts based on the commutation state of the motor 12 meeting the preset commutation threshold. For example, the motor commutation state includes the current commutation number. When the current commutation number is greater than the preset commutation number threshold, the controller determines that the impact mechanism 15 has impacted (but at this time, the actual impact mechanism 15 may not actually have an impact action, that is, the impact block impacts the hammer anvil). The number of impacts is increased by one, and the current number of commutations is restarted. The preset commutation number threshold is related to the reduction ratio of the transmission mechanism 14. The preset commutation number threshold can be preset according to the reduction ratio of the transmission mechanism 14 of the current impact tool. The specific size of the preset commutation number threshold is not specifically limited here. In this embodiment, after the load reaches the preset parameter threshold, the condition characterizing the number of impacts is directly judged, so that even if the impact mechanism 15 fails to actually impact in the first or first few impact cycles when the motor 12 is running at a low speed, it can also actually impact after one or more cycles of stopping and starting the motor 12, and continue to execute the control process of starting after the preset number of impacts occurs and stopping for a preset time. The impact screwdriver 100 can generate continuous low-speed impacts with controllable impact frequency when the motor 12 rotates at a low speed, thereby preventing the impact screwdriver 100 from damaging the operating surface due to excessive impact.

[0104] In some embodiments, the controller 17 is configured to: determine that the load parameter exceeds the preset parameter threshold value based on the fact that the motor 12 does not commutate within the preset commutation duration. Taking the BLDC control of a three-phase brushless motor as an example, the three-phase brushless BLDC motor is controlled by a 6-step commutation method. Optionally, the motor 12 is in a "two-phase conduction, three-phase, six-state" operation mode, and only two-phase windings are turned on in each working state. Therefore, the commutation duration of the motor 12 can be pre-calibrated according to the operating settings of the motor 12. When the motor 12 does not commutate within the preset commutation duration, it means that an impact should have occurred but may not have occurred, that is, the rotational motion of the impact block 152 is blocked, and it is determined that the load parameter exceeds the preset parameter threshold value. In this embodiment, the preset commutation duration includes 40ms.

[0105] In some embodiments, the controller 17 is configured to: determine that the load parameter exceeds a preset parameter threshold according to a phase error in the motor 12. The phase error in the motor 12 refers to a phase deviation error between the three-phase current and the magnetic field in the motor 12, indicating that an impact should have occurred but may not have occurred, resulting in a phase error in the motor 12, so it is determined that the load parameter exceeds the preset parameter threshold.

[0106] refer to Figure 4 The control flow chart for the impact tool in the above embodiment shown specifically includes the following steps:

[0107] S101 : When the impact tool is in a low-speed mode, determining whether it is detected that the impact mechanism applies an impact force to the output shaft.

[0108] If yes, execute step S102, if no, continue to execute S101.

[0109] S102, motor periodic execution: determine that the impact mechanism has impacted a preset number of times, and control the motor to stop for a preset time and then start again.

[0110] In some embodiments, Figure 5 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0111] S201, determining whether the trigger travel is within a preset travel range according to a travel signal of the trigger switch.

[0112] If the trigger travel is within the preset travel range, step S212 is executed; if the trigger travel exceeds the preset travel range, step S222 is executed.

[0113] S212: Determine that the impact tool is in low speed mode.

[0114] S213: Determine whether it is detected that the impact mechanism applies an impact force to the output shaft.

[0115] If yes, execute step S214, if no, continue to execute S213.

[0116] S214, motor periodic execution: determine that the impact mechanism has impacted a preset number of times, and control the motor to stop for a preset time and then start again.

[0117] When the motor is started, the motor is started with a preset acceleration value, wherein the preset acceleration value is greater than the starting acceleration of the impact screwdriver 100 when it is unloaded.

[0118] S222: Determine whether the impact tool is in a non-low-speed mode.

[0119] S223, controlling the motor to continuously rotate and output, so that the impact mechanism produces periodic impacts on the output shaft.

[0120] In some embodiments, Figure 6 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0121] S301, determining whether the trigger travel is within a preset travel range according to a travel signal of the trigger switch.

[0122] If the trigger travel is within the preset travel range, step S312 is executed; if the trigger travel exceeds the preset travel range, step S322 is executed.

[0123] S312: Determine that the impact tool is in low speed mode.

[0124] S313: Determine whether it is detected that the impact mechanism applies an impact force to the output shaft.

[0125] If yes, execute step S314, if no, continue to execute S313.

[0126] S314, motor periodic execution: determine that the impact mechanism has impacted a preset number of times, and control the motor to stop for a preset time and then start again.

[0127] S322: Determine whether the impact tool is in a non-low-speed mode.

[0128] S323, determining a required duty cycle of a motor drive signal of the motor based on the trigger stroke, and outputting the motor drive signal to the motor to control the motor to continuously rotate and output at the required duty cycle.

[0129] In some embodiments, Figure 7 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0130] S401, determining whether the trigger travel is within a preset travel range according to the travel signal of the trigger switch.

[0131] If the trigger travel is within the preset travel range, execute step S412; if the trigger travel exceeds the preset travel range, execute step S422

[0132] S412: Determine that the impact tool is in low speed mode.

[0133] S413: Determine whether it is detected that the impact mechanism applies an impact force to the output shaft.

[0134] If yes, execute step S414, if no, continue to execute S413.

[0135] S414, motor periodic execution: determine the impact mechanism to have a preset number of impacts, control the motor to stop for a preset time, determine the target duty cycle of the motor drive signal of the motor based on the voltage of the battery pack, and control the motor to start running with the target duty cycle.

[0136] S422: Determine whether the impact tool is in a non-low-speed mode.

[0137] S423, determining a required duty cycle of a motor drive signal of the motor based on the trigger stroke, and outputting the motor drive signal to the motor to control the motor to continuously rotate and output at the required duty cycle.

[0138] In some embodiments, Figure 8 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0139] S501, determining whether the trigger travel is within a preset travel range according to the travel signal of the trigger switch.

[0140] If the trigger travel is within the preset travel range, step S512 is executed; if the trigger travel exceeds the preset travel range, step S522 is executed.

[0141] S512: Determine that the impact tool is in low speed mode.

[0142] S513: Determine whether it is detected that the impact mechanism applies an impact force to the output shaft.

[0143] If yes, execute step S514, if no, continue to execute S513.

[0144] S514, the motor executes periodically: obtaining the motor commutation state, determining the number of impacts based on the motor commutation state, determining that the impact mechanism has a preset number of impacts, controlling the motor winding to short-circuit to brake the motor, and determining the target duty cycle of the motor drive signal of the motor based on the voltage of the battery pack after a preset time, and controlling the motor to start running with the target duty cycle.

[0145] When the motor is started, the motor is started with a preset acceleration value, wherein the preset acceleration value is greater than the starting acceleration of the impact screwdriver 100 when it is unloaded.

[0146] S522: Determine whether the impact tool is in a non-low-speed mode.

[0147] S523, determining a required duty cycle of a motor drive signal of the motor based on the trigger stroke, and outputting the motor drive signal to the motor to control the motor to continuously rotate and output at the required duty cycle.

[0148] refer to Fig. 9 The control flow chart for the impact tool in the above embodiment shown specifically includes the following steps:

[0149] S601: When the impact tool is in low speed mode, determine whether a load parameter exceeds a preset parameter threshold.

[0150] If yes, execute step S602, if no, continue to execute S601.

[0151] S602, motor periodic execution: determine whether the impact mechanism meets the condition of a preset number of impacts, and control the motor to stop for a preset time and then start again.

[0152] In some embodiments, Fig.10 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0153] S701: When the impact tool is in low speed mode, determine whether the motor switches phase within a preset switching time.

[0154] If not, execute step S712; if so, execute step S722.

[0155] S712: Determine whether a load parameter exceeds a preset parameter threshold.

[0156] S713, motor periodic execution: determine whether the impact mechanism meets the conditions for a preset number of impacts, and control the motor to stop for a preset time and then start again.

[0157] S722: Determine that the load parameter does not exceed a preset parameter threshold.

[0158] In some embodiments, Fig.11 As shown, the control flow chart of the impact tool in the above embodiment specifically includes the following steps:

[0159] S801. When the impact tool is in low speed mode, determine whether a phase error occurs in the motor.

[0160] If yes, execute step S812, if no, execute step S822.

[0161] S812: Determine whether a load parameter exceeds a preset parameter threshold.

[0162] S813, motor periodic execution: determine whether the impact mechanism meets the conditions for a preset number of impacts, and control the motor to stop for a preset time and then start again.

[0163] S822: Determine that the load parameter does not exceed a preset parameter threshold.

[0164] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present application can be achieved, and this document does not limit this.

[0165] 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, characterized in that: include: a motor including a drive shaft that rotates about a first axis; Output shaft, used for outputting torque externally; An impact mechanism, used for applying an impact force to the output shaft; The impact mechanism includes: 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, used for controlling the motor; Wherein, the controller is configured as: When the impact tool is in low-speed mode, upon detecting that the impact mechanism applies an impact force to the output shaft, the motor periodically performs the following steps: determining that the impact mechanism has impacted a preset number of times, and controlling the motor to stop for a preset time before starting.

2. The impact tool according to claim 1, characterized in that: It also includes a trigger switch for adjusting the rotation speed of the motor. The controller is configured to: determine that the trigger stroke is within a preset stroke range according to a stroke signal of the trigger switch, and determine that the impact tool is in a low-speed mode.

3. The impact tool according to claim 2, characterized in that: The controller is specifically configured as follows: When the trigger stroke exceeds the preset stroke range, it is determined that the impact tool is in a non-low-speed mode, and the motor is controlled to continuously rotate and output, so that the impact mechanism generates periodic impacts on the output shaft.

4. The impact tool according to claim 2, characterized in that: The controller is specifically configured as follows: When the trigger stroke exceeds the preset stroke range, it is determined that the impact tool is in a non-low-speed mode, and a required duty cycle of the motor drive signal of the motor is determined based on the trigger stroke. The motor drive signal is output to the motor to control the motor to continuously rotate and output at the required duty cycle.

5. The impact tool according to any one of claims 1 to 4, characterized in that: The impact tool includes a battery pack for powering the motor, and the controller is configured to: After the motor stops for a preset time, a target duty cycle of a motor driving signal of the motor is determined based on the voltage of the battery pack, and the motor is controlled to start running with the target duty cycle.

6. The impact tool according to claim 5, characterized in that: The target duty cycle is less than or equal to 40%.

7. The impact tool according to any one of claims 1 to 4, characterized in that: The controller is configured to: obtain a motor commutation state, and determine the number of impacts based on the motor commutation state.

8. The impact tool according to any one of claims 1 to 4, characterized in that: The controller is specifically configured to: control the winding of the motor to be short-circuited to brake the motor, and start the motor after the preset time.

9. The impact tool according to any one of claims 1 to 4, characterized in that: The preset number of times includes once.

10. The impact tool according to any one of claims 2 to 4, characterized in that: The preset time is positively correlated with the trigger travel.

11. An impact tool, characterized in that: include: a motor including a drive shaft that rotates about a first axis; Output shaft, used for outputting torque externally; An impact mechanism, used for applying an impact force to the output shaft; The impact mechanism includes: 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, used for controlling the motor; Wherein, the controller is configured as: When the impact tool is in low-speed mode, when the load parameter exceeds a preset parameter threshold, the motor periodically executes: determining that the impact mechanism meets the conditions for a preset number of impacts, and controlling the motor to stop for a preset time and then start.

12. The impact tool according to claim 11, characterized in that: The controller is configured to: According to the fact that the motor does not commutate within a preset commutation time, it is determined that the load parameter exceeds a preset parameter threshold.

13. The impact tool according to claim 11, characterized in that: The controller is configured to: According to a phase error occurring in the motor, it is determined that the load parameter exceeds a preset parameter threshold.

14. The impact tool according to claim 11, characterized in that: The controller is configured to: The commutation state of the motor is acquired, and based on whether the commutation state of the motor satisfies a preset commutation threshold, it is determined that the impact mechanism has impacted a preset number of times.

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