Impact tool and control method thereof

Abstract

The invention discloses an impact tool and a control method thereof. The impact tool includes: a motor; the output shaft is used for outputting torque; the impact mechanism is used for applying impact force to the output shaft; the power switch is used for receiving an operation instruction of a user and controlling the current between the motor and the power supply according to the operation instruction; the controller is used for controlling the operation duty ratio of the motor; the controller is configured as follows: when the impact mechanism applies impact force to the output shaft, the actual load of the output shaft is obtained; and when the actual load is larger than the preset load, the operation duty ratio of the motor is controlled to be adjusted to the target duty ratio at different set rates according to the operation state of the impact tool. By the adoption of the technical scheme, when the impact force generated by the operation instruction input by the user is insufficient, the operation duty ratio of the motor can be increased so as to prevent locked-rotor in the impact process, and the operation stability and the use hand feeling of the user can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of tool equipment, and in particular to an impact tool and a control method thereof. Background Art

[0002] Impact tools refer to electric tools that can output torque at a certain impact frequency. Common impact tools include impact wrenches, impact screwdrivers, and impact drills. Impact tools usually include an output component for outputting rotational force and an impact component for periodically impacting the output component.

[0003] An impact tool in the related art usually has a fixed impact operation mode. For example, during the operation of the impact tool, a fixed torque value is output regardless of whether an impact occurs. As a result, the tool is prone to stalling when the load is large, affecting the operational stability of the impact tool.

[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 and a control method thereof that improves operational stability and user's use feel.

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

[0007] In some embodiments, the present application provides an impact tool, comprising:

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

[0009] A power supply, used to supply power to the motor;

[0010] An output shaft, used for outputting torque;

[0011] An impact mechanism, used for applying an impact force to the output shaft;

[0012] A power switch, used to receive an operation instruction from a user and control the current between the motor and the power supply according to the operation instruction;

[0013] A controller for controlling the operating duty cycle of the motor;

[0014] The controller is configured to: obtain the actual load of the output shaft when the impact mechanism applies impact force to the output shaft; when the actual load is greater than the preset load, control the operating duty cycle of the motor to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool.

[0015] In some embodiments, the impact tool includes a plurality of operating states with different gear positions, rotation directions, and at least one of the remaining power of the power supply.

[0016] In some embodiments, the target duty cycle is different under different operating conditions; the target duty cycle is less than or equal to 50%.

[0017] In some embodiments, the preset load is determined according to the torque value provided by the output shaft under different operating conditions.

[0018] In some embodiments, the impact tool further includes: a switching switch for a user to operate to control the rotation direction of the motor; the rotation direction includes a forward direction and a reverse direction; wherein the set rate in the forward direction is different from the set rate in the reverse direction, and / or the target duty cycle in the forward direction is different from the target duty cycle in the reverse direction.

[0019] In some embodiments, the power switch includes an operating member; before the actual load is greater than a preset load, the operating duty cycle is positively correlated with the stroke amount of the operating member.

[0020] In some embodiments, the controller is further configured to: when the current operating duty cycle of the motor is greater than or equal to the target duty cycle, control the motor to operate at the current operating duty cycle.

[0021] In some embodiments, the controller is further configured to determine the impact force applied by the impact mechanism to the output shaft according to the commutation-related parameters of the motor.

[0022] In some embodiments, the controller is further configured to: when the actual load is less than or equal to the preset load, control the motor to operate at a current operating duty cycle; wherein the current operating duty cycle is determined according to the operating instruction.

[0023] In some embodiments, the present application further provides a method for controlling an impact tool, comprising:

[0024] Obtaining the impact force exerted by the impact mechanism on the output shaft;

[0025] Determine whether the impact force is greater than the preset impact force;

[0026] If yes, the actual load and preset load of the output shaft are obtained;

[0027] Determine whether the actual load is greater than the preset load;

[0028] If so, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool.

[0029] In some embodiments, before controlling the operating duty cycle of the motor to adjust to the target duty cycle at different set rates according to the operating state of the impact tool, the method further includes:

[0030] Determine whether the motor's operating duty cycle is less than a target duty cycle;

[0031] If not, the motor is controlled to run at the current operating duty cycle;

[0032] If so, the step of controlling the operating duty cycle of the motor to be adjusted to the target duty cycle at different set rates is performed according to the operating state of the impact tool.

[0033] The benefit of the present application lies in that the actual load of the output shaft is obtained when the impact mechanism applies an impact force to the output shaft, so that when the actual load is greater than the preset load, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool, so that when the actual load of the impact tool is large, the operating duty cycle of the motor is increased at different set rates to prevent stalling during the impact process. At the same time, the operating duty cycle of the motor is adjusted to the target duty cycle at different set rates instead of directly adjusting the operating duty cycle of the motor to the target duty cycle, so that the impact tool can run smoothly, which is beneficial to improving operational stability and user feel. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure of an impact tool provided in this application;

[0035] Figure 2 A physical diagram of an impact tool provided for the present application;

[0036] Figure 3 A schematic diagram of the structure of an output shaft provided in this application;

[0037] Figure 4 A side view of an output shaft provided in the present application;

[0038] Figure 5 A front view of an output shaft provided in the present application;

[0039] Figure 6 A control circuit diagram of an impact tool provided in this application;

[0040] Figure 7 A flow chart of a control method for an impact tool provided by an embodiment of the present invention;

[0041] Figure 8 A flowchart of another method for controlling an impact tool provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0051] 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.).

[0052] In order to clearly illustrate the technical solution of the present application, an upper side, a lower side, a left side, a right side, a front side and a rear side are defined in the drawings of the specification.

[0053] like Figure 1 and Figure 2 An impact tool of one embodiment of the present application is shown. In this embodiment, the impact tool is specifically an impact wrench 100. It can be understood that in other alternative embodiments, the impact tool can be equipped with different working accessories, and these different working accessories make the impact tool, for example, an impact drill, an impact screwdriver, etc.

[0054] The impact wrench 100 includes a power supply 30. In the present embodiment, the power supply is a DC power supply. The DC power supply is used to provide electrical energy to the impact wrench 100. The DC power supply is a battery pack, and the battery pack cooperates with the corresponding power supply circuit to power the impact wrench 100. Those skilled in the art should understand that the power supply 30 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 power supply is a battery pack, and the battery pack 30 will be used to replace the power supply below, but it cannot be used as a limitation of the present invention.

[0055] like Figure 1 to Figure 2 As shown, the impact wrench 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 an electric 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.

[0056] 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.

[0057] 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.

[0058] Figure 3 This is a schematic diagram of the structure of an output shaft provided in this application. Figure 1-3 As shown, 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 155, and the output shaft 131 is arranged at the front end of the anvil seat 155. It can be understood that the anvil seat 155 and the output shaft 131 can be integrally formed or separately formed as independent parts.

[0059] In some embodiments, Figure 4 A side view of an output shaft provided in the present application. Figure 3and Figure 4 As shown, a groove portion 1311 is provided between the output shaft 131 and the anvil 155. Exemplarily, the length L of the groove portion may be in the range of 0.5-1.8 mm, so as to disperse the stress generated during impact and reduce stress concentration, thereby preventing the output shaft 131 and the anvil from breaking.

[0060] In some embodiments, Figure 5 This is a front view of an output shaft provided in this application. Figure 3 and Figure 5 As shown, when the clamping assembly 132 at the front end of the output shaft 131 clamps the sleeve, a chamfered portion 1312 can be provided on the side wall of the output shaft 131. Exemplarily, the angle α between the chamfered portion and the square shaft plane can range from 0 to 0.8° to reduce the gap between the square shaft of the output shaft and the sleeve, thereby making the output shaft more stable when driving the sleeve to rotate, thereby improving the accuracy of the impact wrench.

[0061] 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.

[0062] 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 a power supply 30.

[0063] 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.

[0064] When the impact tool 100 is working with a load, the output shaft 131 may experience different resistance to rotation due to different load sizes, and the output shaft 131 may reduce its rotation 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 ball to be squeezed and move along the ball track, thereby driving the impact block 152 to move backward 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 overcomes the resistance of the load and continues to rotate a certain angle. Then the output shaft 131 stops again and repeats the above process. 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. When the impact wrench 100 is working without load, the impact mechanism 15 does not impact. The impact mechanism 15 plays a transmission role and transmits the rotation of the motor 12 to the output shaft 131.

[0065] Figure 6 This is a control circuit diagram of an impact tool provided in this application. Figure 1 , 2 As shown in Figures 1 and 6, 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 a delta 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.

[0066] The impact wrench 100 includes a control mechanism 17a. The control mechanism 17a includes a drive circuit 171 and a controller 17. The drive circuit 171 is electrically connected to the stator windings U, V, and W of the motor 12, and is used to transfer the current from the battery pack 30 to the stator windings U, V, and W to drive the motor 12 to rotate. In one embodiment, the drive circuit 171 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate terminal of each switching element is electrically connected to the controller 17 for receiving a control signal from the controller 17. The drain or source of each switching element is connected to the stator windings U, V, and W of the motor 12. The switching 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.

[0067] In this embodiment, the controller 17 is used to control the motor 12. Optionally, the controller 17 is used to control the operating duty cycle of 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.

[0068] The impact wrench 100 further includes a power switch 16. 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, specifically, to receive an operation instruction from the user, and to control the current between the motor 12 and the power supply 30 according to the operation instruction from the user.

[0069] In this embodiment, the controller is configured to: obtain the actual load of the output shaft when the impact mechanism applies impact force to the output shaft; when the actual load is greater than the preset load, control the operating duty cycle of the motor to adjust to the target duty cycle at different set rates based on the operating state of the impact tool.

[0070] When a load is applied to the impact tool 100 and the output shaft 131 completely stops rotating, the impact mechanism 15 will apply an impact force to the output shaft 131 so that the output shaft 131 can overcome the resistance of the load and continue to rotate.

[0071] In this embodiment, the actual load is determined based on at least one of the rotation speed of the output shaft, the rotation angle of the output shaft, and the rotation acceleration of the output shaft.

[0072] In some embodiments, the actual load of the output shaft 131 can be determined based on motor current related parameters. It should be explained that the motor current related parameters include motor current and parameters calculated by the motor current. When the output shaft 131 is loaded with a large load, the current of the motor also increases. When the output shaft 131 is loaded with a small load, the current of the motor 12 also decreases. The motor current can be obtained through a first detection component, and the first detection component includes but is not limited to a current sensing resistor, a Hall current sensor or a mosfet (metal oxide semiconductor field effect transistor) on-resistance, etc.

[0073] In some embodiments, the actual load of the output shaft 131 can also be determined based on parameters related to the motor speed. It should be explained that the parameters related to the motor speed include the motor speed and parameters calculated by the motor speed, such as motor torque, etc. When the output shaft 131 is loaded with a large load, the speed of the output shaft 131 decreases, and the speed of the motor also decreases. When the output shaft 131 is loaded with a small load, the speed of the output shaft 131 increases, and the speed of the motor 12 also increases. The speed of the motor can be obtained through a magnetic ring, a magnetic steel or a photoelectric encoder, or through an inductor, a Hall sensor or a photoelectric sensor.

[0074] In some embodiments, the actual load of the output shaft 131 can also be determined based on the rotation parameters of the output shaft 131. The rotation parameters of the output shaft 131 include at least one parameter of the rotation speed of the output shaft 131, the rotation angle of the output shaft 131, and the rotation acceleration of the output shaft 131. The rotation parameters of the output shaft 131 can be obtained by the second detection component. The second detection component can include, but is not limited to, a position sensor, specifically a photodiode sensor, a magnetic sensor, or a potentiometer. The second detection component can also be a rotation sensor, specifically a gyroscope sensor. The gyroscope sensor can be a single-axis, two-axis, or three-axis micro-electromechanical system (MEMS) sensor or a rotation sensor.

[0075] The preset load can be determined according to the operating state of the impact wrench 100. The output shaft 131 of the impact wrench can provide different torque values ​​under different operating states, and the preset load can be set to different load values. Therefore, the preset load can be determined according to the torque values ​​provided by the output shaft 131 under different operating states. In some embodiments, in one operating state of the impact wrench, the output shaft 131 can provide a smaller torque value, and the preset load is set to a smaller load value; in another operating state of the impact wrench, the output shaft 131 can provide a larger torque value, and the preset load is set to a larger load value.

[0076] The set rate and the target duty cycle can be determined according to the operating state of the impact wrench. In one embodiment, the operating state of the impact wrench includes a plurality of operating states in which at least one of the gear position, the rotation direction, and the remaining power of the power supply is different. Optionally, the set rate is different in different operating states. Optionally, the target duty cycle is different in different operating states. In an exemplary embodiment, Table 1 exemplarily shows the set rate and the target duty cycle of the impact wrench in different operating states.

[0077] Table 1. Set speed and target duty cycle of impact wrench in different operating states

[0078]

[0079] It should be noted that Table 1 only illustrates the values ​​of the target duty cycle and the set rate under some operating conditions, and does not limit the target duty cycle and the set rate. In this embodiment, the target duty cycle is less than or equal to 50%. Since the impact wrench is running at a low speed in a low gear during actual operation, when encountering a large load, it is easy to cause a stall due to the large load. Therefore, the target duty cycle can be limited to less than or equal to 50% to specifically solve the defects of the impact wrench in the related art.

[0080] In some embodiments, the gear of the impact wrench is not limited to the first gear, but may also include the second gear and / or the third gear. When the operating state of the impact wrench includes the second gear, the target duty cycle may be greater than the target duty cycle in the first gear, and the set rate may be greater than the set rate in the first gear.

[0081] Optionally, when the impact mechanism 15 applies an impact force to the output shaft 131, the actual load of the output shaft 131 is obtained. If the actual load is greater than the preset load, it means that the actual load of the output shaft 131 is large, and the speed of the motor 12 under the current operating duty cycle control is not enough to provide sufficient impact force, so that the impact wrench is at risk of stalling. Therefore, the operating duty cycle of the motor 12 can be controlled to adjust to the target duty cycle at a set rate. In this embodiment, when the remaining power of the power supply is low, that is, the battery power is low, the rate of increase of the duty cycle (i.e., acceleration) is greater than when the remaining power of the power supply is high, that is, the battery power is normal, The rate of increase of the duty cycle (i.e., acceleration). Wherein, when δi is equal to 1 millisecond, δx, δy, δx', δy' is less than or equal to 10%. In some embodiments, when δi is equal to 1 millisecond, δx, δy, δx', δy' is less than or equal to 8%.

[0082] In this embodiment, when the impact mechanism applies impact force to the output shaft, the actual load of the output shaft is obtained, so that when the actual load is greater than the preset load, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool. When the actual load of the impact tool is large, the operating duty cycle of the motor is increased at different set rates to prevent stalling during the impact process. At the same time, the operating duty cycle of the motor is adjusted to the target duty cycle at different set rates instead of directly adjusting the operating duty cycle of the motor to the target duty cycle, so that the impact tool can run smoothly, which is beneficial to improving operational stability and user feel.

[0083] The impact wrench 100 further includes a switch 163. The switch 163 is disposed on the upper side of the main switch 16, and the switch 163 is configured to be operated by a user to control the rotation direction of the motor 12, and the rotation direction of the motor 12 may include a forward direction for tightening or screwing in a fastener or a reverse direction for loosening or screwing out a fastener. The set rate in the forward direction is different from the set rate in the reverse direction, and / or the target duty cycle in the forward direction is different from the target duty cycle in the reverse direction, thereby further improving the user's feel of use.

[0084] In this embodiment, the power switch 16 is a travel switch, wherein the travel switch includes an operating member 161 for operation and a sliding rheostat 162. Therefore, the power switch 16 can adjust the signal output by the sliding rheostat 162 by the stroke amount of the operating member 161 being triggered, thereby adjusting the rotation speed of the motor 12, that is, the rotation speed of the motor 12 is adjusted according to the stroke amount of the operating member 161, and the signal output by the sliding rheostat 162 is different when the stroke amount of the operating member 161 is different.

[0085] The duty cycle of the motor 12 is positively correlated with the stroke of the operating member 161, and the duty cycle of the motor 12 is positively correlated with the speed of the motor 12. When the stroke of the operating member 161 is small, the duty cycle of the motor 12 is also small, and at this time, the speed of the motor 12 is also small.

[0086] In some embodiments, the impact wrench 100 stores a mapping relationship between the stroke of the operating member 161 and the PWM signal. The mapping relationship may be linear or non-linear, which is not limited in the embodiments of the present application.

[0087] In an optional embodiment, the controller is further configured to: when the current operating duty cycle of the motor is greater than or equal to the target duty cycle, control the motor to operate at the current operating duty cycle.

[0088] Optionally, the operating duty cycle of the motor 12 is positively correlated with the stroke of the operating member 161. When the stroke of the operating member 161 reaches a maximum value, the operating duty cycle of the motor 12 is also a maximum value in the current operating state. At this time, the operating duty cycle of the motor 12, that is, the current operating duty cycle of the motor 12 is greater than or equal to the target duty cycle. When the current operating duty cycle of the motor 12 is greater than or equal to the target duty cycle, by controlling the motor 12 to operate at the current operating duty cycle, that is, controlling the motor 12 to operate according to the user's operating instructions, so that the impact wrench operates according to the user's operating instructions, the user's feel can be further improved.

[0089] In an optional embodiment, the controller is further configured to: when the actual load is less than or equal to the preset load, control the motor to operate at a current operating duty cycle; wherein the current operating duty cycle is determined according to the operating instruction.

[0090] Optionally, when the impact mechanism 15 applies an impact force to the output shaft 131, the actual load of the output shaft 131 is obtained. If the actual load is less than or equal to the preset load, it means that the actual load of the output shaft 131 is small, and the speed of the motor 12 under the current operating duty cycle control can provide sufficient impact force. Therefore, the motor can be controlled to continue to run at the current operating duty cycle to give the user a better user experience.

[0091] In an optional embodiment, the controller is further configured to determine the impact force applied by the impact mechanism to the output shaft 131 according to commutation-related parameters of the motor.

[0092] When the operating duty cycle 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. The number of rotations of the drive shaft of the motor 12 is related to the rotation angle of the output shaft 131. The commutation-related parameters of the motor 12 are related to the number of rotations of the drive shaft of the motor 12. When an impact occurs, the load of the output shaft 131 changes, and the commutation-related parameters of the motor 12 change. Therefore, the impact force applied by the impact mechanism 15 to the output shaft 131 can be determined based on the commutation-related parameters of the motor 12. Among them, the commutation-related parameters of the motor 12 include: the starting point of the commutation, the end point of the commutation, or at least one of the time required to complete each commutation. By detecting the commutation-related parameters, the changes in the commutation state such as the change in the commutation time, the number of commutation cycles, and the change in the number of commutation cycles can be determined.

[0093] In some embodiments, the impact state of the impact mechanism 15 is determined by the motor current. Whether an impact occurs is determined by the change in current during impact. In other alternative embodiments, various physical signals when an impact occurs, such as electrical signals, audio signals, etc., are detected and collected, and then fed back to the controller to determine that the impact mechanism 15 begins to impact the output shaft 131. In some embodiments, the impact detection unit determines the demagnetization time by detecting the bus voltage, and determines that the impact mechanism 15 begins to impact the output shaft through 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. Therefore, the above does not limit the substantive content of the present invention.

[0094] Based on the same inventive concept, this embodiment also provides a control method for an impact tool. Figure 7 A flowchart of a control method for an impact tool provided by an embodiment of the present invention, referring to Figure 7 As shown, the control method of the impact tool includes:

[0095] S110: Obtain the impact force exerted by the impact mechanism on the output shaft.

[0096] When the impact tool is loaded so that the output shaft stops rotating completely, the impact mechanism will apply an impact force to the output shaft so that the output shaft continues to rotate despite the resistance of the load. In some embodiments, the impact force applied by the impact mechanism to the output shaft can be determined based on the commutation-related parameters of the motor.

[0097] S120, determining whether the impact force is greater than a preset impact force; if so, executing S130.

[0098] The preset impact force may be an impact force that enables the output shaft to overcome the resistance of the load and continue to rotate.

[0099] S130: Obtain the actual load and preset load of the output shaft.

[0100] The preset load may be determined according to the torque value provided by the output shaft under different operating conditions.

[0101] S140, determine whether the actual load is greater than the preset load; if so, execute S150.

[0102] S150, according to the operating state of the impact tool, controlling the operating duty cycle of the motor to be adjusted to the target duty cycle at different set rates.

[0103] The set rate and the target duty cycle can be determined according to the operating state of the impact wrench. In one embodiment, the operating state of the impact wrench includes multiple operating states in which at least one of the gear position, the rotation direction and the remaining power of the power supply is different. In different operating states, the set rate is different. In different operating states, the target duty cycle is different. In some embodiments, the target duty cycle is less than or equal to 50%.

[0104] Specifically, when the impact mechanism applies an impact force to the output shaft, the actual load of the output shaft is obtained. If the actual load is greater than the preset load, it means that the actual load of the output shaft is large, and the speed of the motor under the current operating duty cycle control is not sufficient to provide sufficient impact force, so that the impact wrench is at risk of stalling. Therefore, the operating duty cycle of the motor can be controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool.

[0105] In the present embodiment, when the impact force applied by the impact mechanism to the output shaft is greater than the preset impact force, the actual load of the output shaft is obtained, so that when the actual load is greater than the preset load, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at a set rate according to the operating state of the impact tool. When the actual load of the impact tool is large, the operating duty cycle of the motor is increased at different set rates to prevent stalling during the impact process. At the same time, the operating duty cycle of the motor is adjusted to the target duty cycle at different set rates instead of directly adjusting the operating duty cycle of the motor to the target duty cycle, so that the impact wrench can run smoothly, which is beneficial to improving operational stability and user feel.

[0106] Optional, Figure 8 This is a flow chart of another control method for an impact tool provided by an embodiment of the present invention. Based on the above embodiment, this embodiment further adds a step of how to control the operation of the motor when the motor's operating duty cycle is greater than or equal to the target duty cycle. Figure 8As shown, the control method specifically includes:

[0107] S210: Obtain the impact force exerted by the impact mechanism on the output shaft.

[0108] S220, determining whether the impact force is greater than a preset impact force; if so, executing S230.

[0109] S230: Obtain the actual load and preset load of the output shaft.

[0110] S240, determine whether the actual load is greater than the preset load; if not, execute S250; if so, execute S260.

[0111] S250, controlling the motor to operate at the current operating duty cycle.

[0112] S260, according to the operating state of the impact tool, controlling the operating duty cycle of the motor to be adjusted to the target duty cycle at different set rates.

[0113] Specifically, when the impact force applied by the impact mechanism to the output shaft is greater than the preset impact force, the actual load of the output shaft is obtained. If the actual load is greater than the preset load, it means that the actual load of the output shaft is large, and the speed of the motor under the current operating duty cycle control is insufficient to provide sufficient impact force, so that the impact wrench is at risk of stalling. Therefore, the operating duty cycle of the motor can be controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool. On the contrary, if the actual load is less than or equal to the preset load, it means that the actual load of the output shaft is small, and the speed of the motor under the current operating duty cycle control can provide sufficient impact force. Therefore, the motor can be controlled to continue to run at the current operating duty cycle to give users a better feel.

[0114] In an optional embodiment, the control method of the impact tool further includes: when the current operating duty cycle of the motor is greater than or equal to the target duty cycle, controlling the motor to operate at the current operating duty cycle.

[0115] Specifically, the operating duty cycle of the motor 12 is positively correlated with the stroke of the operating member 161. When the stroke of the operating member reaches the maximum value, the operating duty cycle of the motor is also the maximum value in the current operating state. At this time, the operating duty cycle of the motor, that is, the current operating duty cycle of the motor is greater than or equal to the target duty cycle. When the current operating duty cycle of the motor is greater than or equal to the target duty cycle, by controlling the motor to operate at the current operating duty cycle, that is, controlling the motor to operate according to the user's operating instructions, so that the impact wrench operates according to the user's operating instructions, the user's feel can be further improved.

[0116] In this embodiment, when the impact force applied by the impact mechanism to the output shaft is greater than the preset impact force, the actual load of the output shaft is obtained, so that when the actual load is greater than the preset load, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at a set rate, and when the actual load is less than or equal to the preset load, the motor is controlled to continue to operate at the current operating duty cycle, thereby allowing users to obtain a better user experience.

[0117] 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 rotatable about a first axis; A power supply, used to supply power to the motor; An output shaft, used for outputting torque; An impact mechanism, used for applying an impact force to the output shaft; A power switch, used to receive an operation instruction from a user and control the current between the motor and the power supply according to the operation instruction; A controller for controlling the operating duty cycle of the motor; The controller is configured to: obtain the actual load of the output shaft when the impact mechanism applies an impact force to the output shaft; when the actual load is greater than a preset load, control the operating duty cycle of the motor to be adjusted to a target duty cycle at different set rates according to the operating state of the impact tool.

2. The impact tool according to claim 1, characterized in that The impact tool includes a plurality of operating states in which at least one of a gear position, a rotation direction and a remaining power of the power supply is different.

3. The impact tool according to claim 2, characterized in that In different operating states, the target duty cycle is different; the target duty cycle is less than or equal to 50%.

4. The impact tool according to claim 2, characterized in that The preset load is determined according to the torque value provided by the output shaft under different operating states.

5. The impact tool according to claim 1, characterized in that Also includes: A switch for controlling the rotation direction of the motor by a user; the rotation direction includes a forward direction and a reverse direction; The set rate in the forward direction is different from the set rate in the reverse direction, and / or the target duty cycle in the forward direction is different from the target duty cycle in the reverse direction.

6. The impact tool according to claim 1, characterized in that The power switch includes an operating member; before the actual load is greater than a preset load, the operating duty cycle is positively correlated with the stroke of the operating member.

7. The impact tool according to claim 1, characterized in that The controller is further configured to control the motor to operate at the current operation duty cycle when the current operation duty cycle of the motor is greater than or equal to the target duty cycle.

8. The impact tool according to claim 1, characterized in that The controller is further configured to determine the impact force applied by the impact mechanism to the output shaft according to commutation-related parameters of the motor.

9. The impact tool according to claim 1, characterized in that The controller is further configured to: when the actual load is less than or equal to the preset load, control the motor to operate at the current operating duty cycle; wherein the current operating duty cycle is determined according to the operating instruction.

10. A method for controlling an impact tool, characterized in that: include: Obtaining the impact force exerted by the impact mechanism on the output shaft; Determining whether the impact force is greater than a preset impact force; If yes, obtaining the actual load and preset load of the output shaft; Determining whether the actual load is greater than the preset load; If so, the operating duty cycle of the motor is controlled to be adjusted to the target duty cycle at different set rates according to the operating state of the impact tool.

11. The control method of the impact tool according to claim 10, characterized in that: According to the running state of the impact tool, before the running duty cycle of the motor is controlled to be adjusted to the target duty cycle at different set rates, the method further includes: determining whether the operating duty cycle of the motor is less than the target duty cycle; If not, controlling the motor to operate at the current operating duty cycle; If so, the step of controlling the operating duty cycle of the motor to be adjusted to a target duty cycle at different set rates according to the operating state of the impact tool is executed.

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