Impact tool

Abstract

The invention discloses an impact tool which comprises a motor comprising a motor shaft capable of rotating around a first axis; the battery pack at least supplies power to the motor; the impact assembly can be driven by the motor to provide impact force; the output assembly comprises an output shaft for outputting power; the lowest impact frequency of the impact assembly is less than or equal to 230 BPM. By the adoption of the technical scheme, the impact tool with the low lowest impact frequency can be provided.

Description

Technical Field

[0001] This application relates to the field of power tool technology, specifically to an impact tool. Background Technology

[0002] Impact tools are tools that output rotational motion at a certain impact frequency. Common impact tools include impact wrenches, impact screwdrivers, and impact drills. Impact wrenches are typically used to tighten or loosen bolts and nuts, impact screwdrivers are typically used to loosen or tighten screws, and impact drills are typically used for impact drilling.

[0003] In order to output rotational motion with a certain impact frequency, impact tools typically include an output component for outputting rotational force and an impact component for periodically impacting the output component.

[0004] Generally, the higher the motor speed, the greater the output torque; the lower the motor speed, the smaller the output torque. When the motor runs at a continuous low speed, the torque fluctuates greatly, and there is a chance that the spring tension will exceed the motor torque. The spring will then cause the motor to reverse, making it difficult for the impact tool to impact at a low impact frequency.

[0005] This section provides background information related to this application, which is not necessarily prior art. Summary of the Invention

[0006] One object of this application is to solve or at least mitigate some or all of the aforementioned problems. Therefore, one object of this application is to provide an impact tool with a low minimum impact frequency.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] An impact tool includes: a motor, including a motor shaft rotatable about a first axis; a battery pack, at least powering the motor; an impact assembly, which can be driven by the motor to provide impact force; an output assembly, including an output shaft for outputting power; the minimum impact frequency of the impact assembly is less than or equal to 230 BPM.

[0009] In some embodiments, the minimum impact frequency of the impact component is less than or equal to 200 BPM.

[0010] In some embodiments, the minimum impact frequency of the impact component is less than or equal to 150 BPM.

[0011] In some embodiments, the minimum impact frequency of the impact component is less than or equal to 100 BPM.

[0012] In some embodiments, the minimum impact frequency of the impact component is less than or equal to 70 BPM.

[0013] In some embodiments, the impact tool further includes: a control circuit for controlling the operation of a motor; the control circuit includes a controller; the controller is configured to adjust the change in the duty cycle of a control signal to be greater than or equal to zero when the actual speed of the motor is less than a speed threshold.

[0014] In some embodiments, the controller includes any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

[0015] In some embodiments, an impact tool includes: a motor including a motor shaft rotatable about a first axis; a battery pack for powering at least the motor; an impact assembly capable of being driven by the motor to provide impact force; an output assembly including an output shaft for outputting power; the impact assembly including an elastic element; and a control circuit including at least a controller; the controller being configured to control the output torque of the motor to be greater than the tension of the elastic element when the actual rotational speed of the motor is less than a rotational speed threshold.

[0016] In some embodiments, the controller includes any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

[0017] In some embodiments, the controller is configured to set the duty cycle of the control signal from the previous moment to the duty cycle of the current moment when the actual speed of the motor is less than a speed threshold and the duty cycle of the control signal at the current moment is less than the duty cycle of the control signal at the previous moment.

[0018] In some embodiments, an impact tool includes: a motor including a motor shaft rotatable about a first axis; a battery pack for powering at least the motor; an impact assembly capable of being driven by the motor to provide impact force; an output assembly including an output shaft for outputting power; and a control circuit including at least a controller; the controller being configured to adjust the duty cycle of a control signal at the current moment to be at least not less than the duty cycle of the control signal at the previous moment when the actual rotational speed of the motor is less than a rotational speed threshold.

[0019] In some embodiments, the controller includes any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

[0020] The advantage of this application is that it can provide an impact tool with a low minimum impact frequency. Attached Figure Description

[0021] Figure 1 This is a perspective view of an embodiment of an impact wrench;

[0022] Figure 2 yes Figure 1 A cross-sectional view of an impact wrench;

[0023] Figure 3 yes Figure 1 Exploded 3D view of the impact component of the impact wrench in the image;

[0024] Figure 4 yes Figure 1 The circuit block diagram of the impact wrench in the image;

[0025] Figure 5 This is a flowchart illustrating one embodiment of a controller controlling the output torque of a motor to be greater than the tension of an elastic element.

[0026] Figure 6 This is a flowchart illustrating another implementation method in which the controller controls the output torque of the motor to be greater than the tension of the elastic element. Detailed Implementation

[0027] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0028] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0029] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0030] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0031] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0032] In this application, those skilled in the art will understand 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.

[0033] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0034] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0035] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0036] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0037] like Figures 1 to 2 An embodiment of the impact tool of this application is shown. In this embodiment, the impact tool is an impact wrench 100. It is understood that the impact tool is a rotary tool. In other alternative embodiments, the rotary tool can be equipped with different working attachments, which enable the impact tool to be, for example, an impact screwdriver, an impact drill, or other impact tools.

[0038] like Figure 1 An impact wrench 100 according to an embodiment of this application is shown, including a power supply. The power supply provides electrical energy to the impact wrench 100. In this embodiment, the power supply includes a DC power supply 200, such as a battery pack. The battery pack, in conjunction with a corresponding power circuit, supplies power to the corresponding components within the impact wrench 100. Those skilled in the art should understand that the power supply is not limited to the use of a battery pack; it can also be powered by mains power or AC power, in conjunction with corresponding rectification, filtering, and voltage regulation circuits, to supply power to the corresponding components within the machine. In this embodiment, the DC power supply 200 is specifically configured as a battery pack; hereinafter, "battery pack 200" will be used to refer to the DC power supply, but this should not be construed as a limitation of this application.

[0039] like Figures 1 to 2 As shown, the impact wrench 100 includes a housing 110, a motor 120, an output assembly 130, a transmission assembly 140, and an impact assembly 150. The motor 120 includes a drive shaft 121 that rotates about a first axis 101. The motor 120 includes a stator assembly 122 and a rotor assembly 123. The rotor assembly 123 is formed with or connected to the drive shaft 121 that rotates about the first axis 101. In this embodiment, the motor 120 is an inner rotor brushless motor. In other alternative embodiments, the motor 120 is an outer rotor brushless motor. For an inner rotor motor, the stator assembly 122 is sleeved outside the rotor assembly 123. For an outer rotor motor, the rotor assembly 123 is sleeved outside the stator assembly 122. In this embodiment, the brushless motor is configured as a three-phase brushless motor. It is understood that the motor is not limited to a three-phase brushless motor and can also be other types of DC motors; this does not affect the substantive content of this application.

[0040] The housing 110 includes a motor housing 111 for accommodating a motor 120 and an output housing 112 for accommodating at least a portion of the output assembly 130, the output housing 112 being connected to the front end of the motor housing 111. The housing 110 also forms or is connected to a user-operated grip portion 113. The grip portion 113 and the motor housing 111 form a T-shaped or L-shaped structure for easy gripping and operation by the user. One end of the grip portion 113 is connected to a battery pack 200. The battery pack 200 is detachably connected to the grip portion 113.

[0041] like Figure 1 As shown, the impact wrench 100 also includes a switch 160, which is a trigger switch. The trigger switch is provided on the grip 113 for the user to operate and control the impact wrench 100.

[0042] The output assembly 130 includes an output shaft 131 for connecting and driving the working attachment to rotate. The front end of the output shaft 131 is provided with a clamping assembly, which can clamp the corresponding working attachment, such as a screwdriver bit, drill bit, or socket, when performing different functions.

[0043] The output shaft 131 is used to output power, and it rotates about the output axis 102. In this embodiment, the first axis 101 coincides with the output axis 102. In other alternative embodiments, the output axis 102 and the first axis 101 are set at a certain angle. In other alternative embodiments, the first axis 101 and the output axis 102 are parallel to each other but do not coincide.

[0044] like Figures 2 to 3 As shown, the impact assembly 150 is used to provide impact force to the output shaft 131. The impact assembly 150 includes a main shaft 151, an impact block 152 sleeved on the outer periphery of the main shaft 151, a hammer anvil 153 disposed at the front end of the impact block 152, and an elastic element 154. The hammer anvil 153 is connected to the output shaft 131. The output shaft 131 is formed or connected to the front end of the hammer anvil 153. It is understood that the hammer anvil 153 and the output shaft 131 can be integrally formed or separately formed independent parts.

[0045] The impact block 152 is driven to rotate by the drive shaft 121, and the hammer anvil 153 cooperates with and is struck by the impact block 152. The main shaft 151 connects the impact block 152 and the drive shaft 121. In some embodiments, the drive shaft 121 drives the main shaft 151, and the main shaft 151 drives the impact block 152 to rotate.

[0046] The output shaft 131 extends out of the output housing 112. The impact block 152 is supported on the main shaft 151, rotates integrally with the main shaft 151, and can reciprocate relative to the main shaft 151 in the axial direction of the main shaft. In some embodiments, the axis of the main shaft 151 coincides with the axis of the drive shaft 121; therefore, the impact block 152 reciprocates and rotates relative to the main shaft 151 along the direction of the first axis 101. In some embodiments, the axis of the main shaft 151 may be parallel to but not coincident with the axis of the drive shaft 121, or the axis of the main shaft 151 may be set at a certain angle to the axis of the drive shaft 121.

[0047] The elastic element 154 provides a force to the impact block 152 to bring it closer to the anvil 153. Optionally, the elastic element 154 can be a coil spring. During the operation of the impact wrench 100, the impact block 152 rotates integrally with the spindle 151 while reciprocating back and forth relative to the spindle 151 along the first axis 101 with a predetermined stroke.

[0048] When the impact wrench 100 is unloaded, the impact assembly 150 does not impact; instead, it acts as a transmission mechanism, transmitting the rotation of the motor 12 to the output shaft 131. When a load is applied to the impact wrench 100, the rotation of the output shaft 131 is hindered. Depending on the load, the output shaft 131 may rotate at a reduced speed or stop completely. When the output shaft 131 stops rotating completely, the hammer anvil 153 also stops rotating and completely disengages from the impact block 152. The main shaft 151 drives the impact block 152 to rotate at a certain speed, and the elastic element 154 rebounds axially. The relative rotational speed between the impact block 152 and the hammer anvil 153 is the rotational speed of the impact block 152. When the impact block 152 rotates to contact the hammer anvil 153, it applies an impact force to the hammer anvil 153. Under the action of this impact force, the output shaft 131 continues to rotate at a certain angle to overcome the load. Then the output shaft 131 stops rotating again and repeats the above process. Since the impact frequency is large enough, a relatively continuous impact force will be generated on the output shaft 131, so that the working accessory can work continuously.

[0049] The transmission assembly 140 is configured to transmit the torque output from the drive shaft 121 to the output shaft 131. In this embodiment, the transmission assembly 140 is disposed between the motor 120 and the impact assembly 150, for transmitting power between the drive shaft 121 and the main shaft 151. In this embodiment, the transmission assembly 140 employs a planetary gear reduction. Since the working principle of planetary gear reduction and the reduction generated by such a transmission assembly are well disclosed to those skilled in the art, detailed descriptions are omitted here for the sake of brevity.

[0050] refer to Figure 4 The circuit block diagram of the impact wrench 100 shown indicates that the drive system of the motor 120 may include at least a DC power supply 200 (i.e., battery pack 200), a control circuit 300, and a parameter detection module 400. The control circuit 300 may include a drive circuit 310 and a controller 320.

[0051] In this embodiment, motor 120 is an internal rotor brushless motor. In other alternative embodiments, motor 120 is an external rotor brushless motor. In this embodiment, the brushless motor is configured as a three-phase brushless motor. It is understood that the motor is not limited to a three-phase brushless motor, and can also be other types of DC motors, which does not affect the substantive content of this application. Motor 120 includes at least three-phase stator windings A, B, and C, which can be connected in a star or delta configuration.

[0052] The drive circuit 310 is electrically connected to the stator windings A, B, and C of the motor 120, and is used to transfer current from the battery pack 200 to the stator windings A, B, and C to drive the motor 120 to rotate. In one embodiment, the drive circuit 310 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, and Q6, arranged in the current path from the battery pack 200 to the motor 120. Q1, Q3, and Q5 are high-side switching elements, and Q2, Q4, and Q6 are low-side switching elements. Any phase of the stator winding of the motor 120 is connected to one high-side switching element and one low-side switching element.

[0053] In the drive circuit 310, the gate of each switching element is electrically connected to the controller 320 to receive a control signal from the controller 320, which may be a PWM signal. The controller 320 can output a control signal to control the switching elements in the drive circuit 310 to conduct and form a freewheeling state. The drain or source of each switching element is connected to the stator windings A, B, and C of the motor 120. Switching elements Q1-Q6 receive control signals from the controller 320 and change their respective conduction states, thereby changing the current applied by the power supply 200 to the stator windings A, B, and C of the motor 120. In one embodiment, the drive circuit 310 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.). It is understood that the aforementioned switching elements may also be any other type of solid-state switch, such as an insulated-gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), etc.

[0054] In order to drive Figure 4 The motor 120 shown rotates, and the drive circuit 310 has multiple drive states. Under different drive states, the speed or direction of the motor 120 can be different.

[0055] In some embodiments, such as Figure 4 The impact wrench 100 shown includes a parameter detection module 400, which can detect the operating parameters of the motor 120 when it is running, such as the rotational speed of the motor 120.

[0056] In some embodiments, the controller 320 may be any one of a PI controller, a PID controller, a P controller, or a LADRC controller, and this application does not limit it.

[0057] In certain operating conditions, such as when tightening small screws, to prevent excessive impact frequency of the impact wrench 100 from causing surface damage, the impact frequency of the impact wrench 100 needs to be kept within a small range. The impact frequency of the impact wrench 100 is directly proportional to the rotational speed of the motor 120; therefore, the motor 120 needs to operate at a consistently low speed. However, when the motor 120 operates at a consistently low speed, its torque fluctuates significantly. If the torque at a later moment is less than the torque at a previous moment, the torque of the motor 120 may not be able to overcome the tension of the elastic element 154, causing the elastic element 154 to drive the motor 120, which is rotating in the forward direction, to reverse. Therefore, when a low impact frequency of the impact wrench 100 is required, the motor 120 needs to overcome the possibility of reverse rotation at low speeds and low torques to ensure that the impact wrench 100 can operate at a low impact frequency.

[0058] In some embodiments, the minimum impact frequency of the impact component 150 is less than or equal to 230 BPM. In some embodiments, the minimum impact frequency of the impact component 150 is less than or equal to 200 BPM. In some embodiments, the minimum impact frequency of the impact component 150 is less than or equal to 150 BPM. In some embodiments, the minimum impact frequency of the impact component 150 is less than or equal to 100 BPM. In some embodiments, the minimum impact frequency of the impact component 150 is less than or equal to 70 BPM.

[0059] In some embodiments, when the impact frequency of the impact wrench 100 needs to be relatively low, i.e., when the motor 120 needs to operate at a lower speed, if the actual speed of the motor 120 is less than a speed threshold, the controller 320 controls the output torque of the motor 120 to be greater than the tension of the elastic element 154, thereby preventing the elastic element 154 from causing the motor 120 to reverse. The actual speed of the motor 120 is detected by the parameter detection module 400 and transmitted to the controller 320. The speed threshold of the motor 120 is set according to the speed corresponding to the lower impact frequency required by the impact assembly 150.

[0060] In some embodiments, the controller 320 controls the output torque of the motor 120 to be greater than the tension of the elastic element 154, including a first implementation: when the actual speed of the motor 120 is less than a speed threshold, and the duty cycle of the control signal at the current moment is less than the duty cycle of the control signal at the previous moment, the duty cycle of the control signal at the previous moment is set to the duty cycle at the current moment. Optionally, the speed threshold is greater than or equal to the speed of the motor 120 corresponding to the lowest impact frequency of the impact component 150. For example, when the lowest impact frequency of the impact component 150 is 60 BPM, the corresponding speed of the motor 120 is 210 RPM, so the speed threshold can be 210 RPM, or the speed threshold can also be greater than 210 RPM, such as setting the speed threshold to 600 RPM.

[0061] Combination Figure 5 The first method to achieve a controller 320 controlling the output torque of motor 120 to be greater than the tension of elastic element 154 includes the following steps:

[0062] S501: Obtain the motor's speed threshold and the actual speed at the current moment.

[0063] The controller 320 acquires the speed threshold of the motor 120 and the actual speed at the current moment. The actual speed at the current moment is detected by the parameter detection module 400 and transmitted to the controller 320.

[0064] S502: Obtain the duty cycle of the control signal of the motor at the current moment and the duty cycle of the control signal at the previous moment.

[0065] The controller 320 acquires the duty cycle of the control signal of the motor 120 at the current moment and the duty cycle of the control signal at the previous moment. The duty cycle of the control signal at the current moment and the duty cycle of the control signal at the previous moment are both detected by the parameter detection module 400 and transmitted to the controller 320.

[0066] S503: Determine the relationship between the actual speed of the motor at the current moment and the speed threshold, as well as the relationship between the duty cycle of the control signal at the current moment and the duty cycle of the control signal at the previous moment.

[0067] After obtaining the actual speed and speed threshold of motor 120 at the current moment in S501, controller 320 needs to determine the relationship between the actual speed and speed threshold of motor 120 at the current moment. After obtaining the duty cycle of the control signal of motor 120 at the current moment and the duty cycle of the control signal at the previous moment in S502, controller 320 needs to determine the relationship between the duty cycle of the control signal of motor 120 at the current moment and the duty cycle of the control signal at the previous moment. If controller 320 determines that the actual speed of motor 120 at the current moment is less than the speed threshold, and the duty cycle of the control signal at the current moment is less than the duty cycle of the control signal at the previous moment, it jumps to step S504; otherwise, the loop ends. Among them, if the actual speed of motor 120 at the current moment is less than the speed threshold, it means that the impact wrench 100 can still impact at a set lower impact frequency. If the duty cycle of the control signal at the current moment is less than the duty cycle of the control signal at the previous moment, it means that the actual speed of motor 120 at the current moment is less than the speed at the previous moment. The torque output by motor 120 at this moment is less than the torque output at the previous moment, which may cause the elastic element 154 to drive motor 120 to reverse.

[0068] S504: Set the duty cycle of the control signal from the previous moment to the duty cycle of the control signal at the current moment.

[0069] In S503, after the controller 320 determines that the actual speed of the motor 120 at the current moment is less than the speed threshold and the duty cycle of the control signal at the current moment is less than the duty cycle of the control signal at the previous moment, the controller 320 sets the duty cycle of the control signal at the previous moment to the duty cycle of the control signal at the current moment. Therefore, the torque output by the motor 120 at the current moment will not be less than the torque output by the motor 120 at the previous moment. This prevents the motor 120 from being unable to overcome the tension of the elastic element 154 due to insufficient torque at the current moment, ensuring that the motor 120 will not be reversed by the elastic element 154 when the impact wrench 100 impacts at low frequency, allowing the impact wrench 100 to impact at a lower frequency.

[0070] In some embodiments, the rotational speed of the motor 120 is set to A when the impact frequency of the impact component 150 is 70 BPM, and the rotational speed threshold of the motor 120 is A1, where A1 is greater than or equal to A. The parameter detection module 400 detects that the rotational speed of the motor 120 at the current time t is B1, the duty cycle of the control signal is C1, and the parameter detection module 400 transmits the rotational speed B1 and the duty cycle C1 of the motor 120 to the controller 320. The controller 320 compares the obtained rotational speed B1 of the motor 120 with the rotational speed threshold A1 of the motor 120, and determines that the actual rotational speed B1 of the motor 120 at the current time t is less than the rotational speed threshold A1 of the motor 120. Furthermore, the controller 320 compares the duty cycle C1 of the motor 120 with the duty cycle C2 of the control signal of the motor 120 at time t-1, and determines that the duty cycle of the motor 120 at the current time t is less than the duty cycle of the motor 120 at time t-1. That is, the speed B1 of the motor 120 at the current time t is less than the speed B2 of the motor 120 at time t-1, and the torque output by the motor 120 at the current time t is less than the torque output by the motor 120 at time t-1. Therefore, the controller 320 controls the duty cycle of the motor 120 at the current time t to change from C1 to C2. Thus, the speed B1 of the motor 120 at time t is controlled by the controller 320 to be greater than or equal to the speed B2 at time t-1. Similarly, the torque output by the motor 120 at time t is also controlled by the controller 320 to be greater than or equal to the torque at time t-1. This ensures that when the impact component 150 is at a low impact frequency, the torque output by the motor 120 at each subsequent moment is always greater than or equal to the torque output at the previous moment. Therefore, the motor 120 will not be unable to overcome the tension of the elastic element 154 at a subsequent moment. This also ensures that when the impact frequency of the impact wrench 100 is low, the motor 120 can always maintain forward rotation and will not be driven to reverse rotation by the elastic element 154.

[0071] In some embodiments, the controller 320 controls the output torque of the motor 120 to be greater than the tension of the elastic element 154 in a second implementation: when the actual speed of the motor 120 is less than a speed threshold, the controller 320 adjusts the change in the duty cycle of the control signal to be greater than or equal to zero. Here, the change in the duty cycle of the control signal refers to the difference between the duty cycle of the control signal at the current moment and the control signal at the previous moment. A change in the duty cycle of the control signal greater than or equal to zero means that the duty cycle of the control signal at the current moment is at least not less than the duty cycle of the control signal at the previous moment.

[0072] Combination Figure 6 The second method to achieve a controller 320 controlling the output torque of motor 120 to be greater than the tension of elastic element 154 includes the following steps:

[0073] S601: Obtain the motor's speed threshold and the actual speed at the current moment.

[0074] The controller 320 acquires the speed threshold of the motor 120 and the actual speed at the current moment. The actual speed at the current moment is detected by the parameter detection module 400 and transmitted to the controller 320.

[0075] S602: Determine the relationship between the motor's current actual speed and the speed threshold.

[0076] After obtaining the actual speed and speed threshold of motor 120 at the current moment in step S601, controller 320 needs to determine the relationship between the actual speed of motor 120 at the current moment and the speed threshold. If controller 320 determines that the actual speed of motor 120 at the current moment is less than the speed threshold, it jumps to step S603; otherwise, the loop ends.

[0077] S603: Adjust the change in the duty cycle of the control signal to be greater than or equal to zero.

[0078] In S602, after the controller 320 determines that the actual speed of the motor 120 at the current moment is less than the speed threshold, the controller 320 controls the duty cycle of the control signal of the motor 120 at the current moment to be greater than or equal to the duty cycle of the control signal at the previous moment, so that the change in the duty cycle of the control signal is always greater than or equal to zero. Therefore, the torque output by the motor 120 at the current moment is greater than or equal to the torque output by the motor 120 at the previous moment. That is, during the low-speed compression of the elastic element 154 by the motor 120, the torque remains constant or continuously increases, so that the torque does not fluctuate. This achieves the desired torque control when the motor 120 is subjected to low-frequency impact from the impact wrench 100.

[0079] This ensures that the motor 120 will not be reversed by the elastic element 154 when the impact wrench 100 impacts at low frequency, so that the impact wrench 100 can impact at a lower frequency.

[0080] In some embodiments, proportional adjustment can be used to make the change in the duty cycle of the control signal greater than or equal to zero by the controller 320. A proportional relationship is set between the change in the duty cycle of the control signal and the speed difference of the motor 120. The change in the duty cycle of the control signal is equal to the product of the speed difference of the motor 120 and the proportional relationship.

[0081] Optionally, the speed difference of motor 120 refers to the difference between the speed threshold of motor 120 and the actual speed at the current moment. When the actual speed at the current moment is less than the speed threshold, the speed difference of motor 120 is always greater than zero, thus the proportional relationship is positive, making the change in the duty cycle of the control signal always greater than or equal to zero. Alternatively, the speed difference of motor 120 refers to the difference between the actual speed of motor 120 at the current moment and the speed threshold. When the actual speed at the current moment is less than the speed threshold, the speed difference of motor 120 is always greater than zero, thus the proportional relationship is negative, making the change in the duty cycle of the control signal always greater than or equal to zero.

[0082] In this application, two methods are used to ensure that when the speed of the motor 120 is low, the torque of the motor 120 does not fluctuate but remains constant or continues to increase, so that the output torque of the motor 120 is always greater than the tension of the elastic element 154, thereby enabling the impact wrench 100 to work at a lower impact frequency.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. An impact tool, comprising: a motor including a motor shaft rotatable about a first axis; a battery pack powering at least the motor; an impact assembly drivable by the motor to provide an impact force; an output assembly including an output shaft for outputting power; characterized in that a minimum impact frequency of the impact assembly is less than or equal to 230 BPM.

2. The impact tool according to claim 1, wherein a minimum impact frequency of the impact assembly is less than or equal to 200 BPM.

3. The impact tool according to claim 1, wherein a minimum impact frequency of the impact assembly is less than or equal to 150 BPM.

4. The impact tool of claim 1, wherein a minimum impact frequency of the impact assembly is less than or equal to 100 BPM.

5. The impact tool of claim 1, wherein a minimum impact frequency of the impact assembly is less than or equal to 70 BPM.

6. The impact tool of claim 1, wherein the impact tool further comprising: a control circuit for controlling operation of the motor; the control circuit including a controller; the controller configured to adjust a change in duty cycle of a control signal to be greater than or equal to zero if an actual speed of the motor is less than a speed threshold.

7. The impact tool according to claim 6, wherein the controller including any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

8. An impact tool, comprising: a motor including a motor shaft rotatable about a first axis; a battery pack powering at least the motor; an impact assembly drivable by the motor to provide an impact force; an output assembly including an output shaft for outputting power; the impact assembly including an elastic element; a control circuit including at least a controller; characterized in that the controller is configured to control an output torque of the motor to be greater than a tension of the elastic element if an actual speed of the motor is less than a speed threshold.

9. The impact tool according to claim 8, wherein the controller including any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

10. The impact tool of claim 8, wherein the controller configured to set a duty cycle of the control signal at a current time to be a duty cycle of the control signal at a previous time if the actual speed of the motor is less than the speed threshold and the duty cycle of the control signal at the current time is less than the duty cycle of the control signal at the previous time.

11. An impact tool, comprising: a motor including a motor shaft rotatable about a first axis; a battery pack powering at least the motor; an impact assembly drivable by the motor to provide an impact force; an output assembly including an output shaft for outputting power; a control circuit including at least a controller; characterized in that the controller is configured to adjust a duty cycle of a control signal at a current time to be at least not less than a duty cycle of the control signal at a previous time if an actual speed of the motor is less than a speed threshold.

12. The impact tool of claim 11, wherein the controller including any one of a PI controller, a PID controller, a P controller, and a LADRC controller.

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