Impact tool

Abstract

An impact tool, comprising: an impact mechanism (15), which applies an impact force to an output shaft (131), the impact mechanism comprising an impact block (152) driven by a motor (12) and a hammer anvil (153) matching the impact block and impacted by the impact block; a transmission mechanism (14), which is configured to transmit to the output shaft torque output by a driving shaft (121), the transmission mechanism comprising a multi-stage transmission assembly (140); and a direct-current power supply (30), which at least supplies power to the motor, the nominal voltage of the direct-current power supply being less than 18 V, and the fastening torque of the output shaft on a workpiece being greater than or equal to 170 N•m. The impact tool is powered by a low nominal voltage to output large torque.

Description

impact tools

[0001] This application claims priority to the Chinese patent application with application number 202311788228.7 filed with the China Patent Office on December 22, 2023 and the Chinese patent application with application number 202323530966.X. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power tools, for example, to an impact tool. Background Art

[0003] Impact tools are tools that generate or achieve rotational motion at a specific impact frequency. Common impact tools include impact wrenches, impact screwdrivers, and impact drills. Impact wrenches are typically used to tighten bolts and nuts, impact screwdrivers are typically used to loosen or tighten screws, and impact drills are typically used to drill holes.

[0004] In order to generate a rotational motion with a certain impact frequency, the impact tool generally includes an output component for outputting a rotational force and an impact mechanism for periodically impacting the output component.

[0005] In related technical products, the greater the output impact torque, the higher the output power of the DC power supply required by the impact tool, and the higher the output torque of the impact tool.

[0006] This section provides background information related to the present application which is not necessarily prior art. Summary of the Invention

[0007] The present application can solve or at least alleviate part or all of the above problems. To this end, the present application provides a high-torque impact tool powered by a low nominal voltage.

[0008] An impact tool comprises: a motor including a drive shaft rotating about a first axis; an output shaft including a self-defined output axis, the output shaft rotating about the output axis to output power; a tightening torque of the output shaft on a workpiece greater than or equal to 170 N·m; an impact mechanism applying an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor and a hammer anvil cooperating with and impacted by the impact block; a transmission mechanism configured to transmit the torque output by the drive shaft to the output shaft, the transmission mechanism comprising a multi-stage transmission assembly; and a DC power supply for powering at least the motor, the nominal voltage of the DC power supply being less than 18V.

[0009] In some embodiments, the multi-stage transmission assembly includes at least two stages of planetary gear reduction assemblies.

[0010] In some embodiments, the multi-stage transmission assembly includes: a first planetary carrier, arranged in front of the motor; a first planetary gear, supported by the first planetary carrier; a second planetary carrier, arranged in front of the first planetary carrier; a second planetary gear, supported by the second planetary carrier; and an inner ring gear, causing at least the second planetary gear to perform planetary motion.

[0011] In some embodiments, the outer diameter of the inner ring gear is less than or equal to 50 mm.

[0012] In some embodiments, the impact mechanism further includes a main shaft connecting the impact block and the drive shaft and a first bearing supporting the main shaft for rotation, wherein the first bearing limits the axial displacement of the inner gear ring.

[0013] In some embodiments, the first bearing partially overlaps with the second planet carrier along the first axis direction.

[0014] In some embodiments, the ratio of the rotational speed of the drive shaft to the rotational speed of the main shaft is substantially constant.

[0015] In some embodiments, the speed ratio from the drive shaft to the main shaft is greater than or equal to 9.

[0016] In some embodiments, the inner ring gear causes the first planetary gear and the second planetary gear to perform planetary motion respectively.

[0017] In some embodiments, the maximum rotational speed of the output shaft is less than or equal to 3000 rpm.

[0018] In some embodiments, the nominal voltage of the DC power supply is greater than or equal to 3V and less than or equal to 9V.

[0019] In some embodiments, the motor further includes a housing having a receiving space, wherein the motor is disposed in the receiving space, and a distance L1 from the rear end of the housing to the front end of the output shaft is less than or equal to 145 mm.

[0020] In some embodiments, a distance L1 from the rear end of the housing to the front end of the output shaft is less than or equal to 135 mm.

[0021] In some embodiments, the transmission mechanism further includes a housing assembly, the housing assembly including a first recessed portion disposed on the outside and extending inward, and a second recessed portion disposed on the inside and extending outward, the first recessed portion and the second recessed portion being circumferentially spaced apart.

[0022] In some embodiments, the diameter of the impact block is greater than or equal to 40 mm, and the mass of the impact block is greater than or equal to 120 g.

[0023] An impact tool comprises: a motor including a drive shaft rotating about a first axis; an output shaft including a self-defined output axis, the output shaft rotating about the output axis to output power; a tightening torque of the output shaft on a workpiece greater than or equal to 170 N·m; an impact mechanism for applying an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor and an anvil mating with and impacted by the impact block; a transmission mechanism configured to transmit the torque output by the drive shaft to the output shaft; and a DC power supply for powering at least the motor, wherein the nominal voltage of the DC power supply is greater than or equal to 3V and less than or equal to 9V.

[0024] An impact tool comprises: a motor including a drive shaft rotating about a first axis; an output shaft including a self-defined output axis, the output shaft rotating about the output axis to output power; wherein the output shaft has a tightening torque on a workpiece greater than or equal to 170 N·m; an impact mechanism for applying an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor, an anvil mating with and impacted by the impact block, and a spindle connecting the impact block and the drive shaft; a transmission mechanism configured to transmit the torque output by the drive shaft to the spindle; wherein the speed ratio from the drive shaft to the spindle is greater than or equal to 9; and a DC power supply for supplying power to at least the motor, the nominal voltage of the DC power supply being greater than or equal to 3V and less than or equal to 9V.

[0025] In some embodiments, the transmission mechanism includes a multi-stage transmission assembly; the multi-stage transmission assembly includes at least two stages of planetary gear reduction assemblies.

[0026] In some embodiments, the transmission mechanism includes: a first planetary carrier, arranged in front of the motor; a first planetary gear, supported by the first planetary carrier; a second planetary carrier, arranged in front of the first planetary carrier; a second planetary gear, supported by the second planetary carrier; and an inner ring gear, which at least causes the second planetary gear to perform planetary motion.

[0027] In some embodiments, the ratio of the rotational speed of the drive shaft to the rotational speed of the main shaft is substantially constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a structural diagram of an impact tool according to an embodiment of the present application;

[0029] FIG2 is a cross-sectional view of an impact tool according to an embodiment of the present application;

[0030] FIG3 is a schematic diagram of an exploded view of an impact tool according to an embodiment of the present application;

[0031] FIG4 is a schematic diagram of a partial exploded view of an impact tool according to an embodiment of the present application;

[0032] FIG5 is a schematic diagram of a partial exploded view of an impact tool according to an embodiment of the present application;

[0033] FIG6 is a schematic diagram of a partial exploded view of an impact tool according to an embodiment of the present application from another perspective;

[0034] FIG7 is a structural diagram of some components of the impact tool in FIG6;

[0035] FIG8 is a schematic diagram of some components of the impact tool of FIG7 from another perspective;

[0036] FIG9 is an AA sectional view of part of the impact tool and an exploded view of the inner gear ring component in FIG8 ;

[0037] FIG10 is a partial exploded view of a battery pack according to an embodiment of the present application;

[0038] FIG11 is a partial exploded view of a battery pack according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] Before any embodiments of the present 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 foregoing drawings.

[0040] In this application, the terms "comprises," "includes," "has," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0041] In this application, the term "and / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this application generally indicates that the related objects are in an "and / or" relationship.

[0042] In this 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, a direct connection refers to two parts or components being connected together without an intermediary, and an indirect connection refers to two parts or components being connected to at least one intermediary, with the two parts or components being connected via the intermediary. Furthermore, "connect" and "couple" are not limited to physical or mechanical connections or couplings and may include electrical connections or couplings.

[0043] In this application, it will be understood by those skilled 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 tolerance caused by manufacturing, assembly, use, etc. associated with a specific value. 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).

[0044] In this application, it will be understood by those skilled in the art that the function performed by an assembly can be performed by one assembly, multiple assemblies, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one assembly, or a combination of multiple parts.

[0045] 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 the other element "upper" or "lower", but also be indirectly connected to the other 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, below can include directly below, lower left, lower right, lower front and lower back, etc.

[0046] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. Where a unit "controller," "processor," "central processing unit," "CPU," or "MCU" is used to perform a particular function, unless otherwise specified, the function may be performed by a single unit or multiple units.

[0047] In this application, the terms "device", "module" or "unit" can be implemented in the form of hardware or software to achieve specific functions.

[0048] 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.).

[0049] In order to clearly illustrate the technical solution of the present application, the upper side, lower side, front side and rear side are also defined as shown in FIG1 .

[0050] 1 and 2 illustrate an impact tool according to a first embodiment of the present application. In this embodiment, the impact tool is an impact wrench 100. It will be appreciated that the impact tool is a rotary tool. In other alternative embodiments, the rotary tool may be equipped with various working accessories. By installing these various working accessories, the impact tool may be an impact screwdriver, an impact drill, or other impact tool.

[0051] As shown in FIG1 , an impact wrench 100 according to an embodiment of the present application includes a power supply, which provides electrical energy to the impact wrench 100. In this embodiment, the power supply includes a DC power supply 30, for example, the DC power supply 30 is a battery pack, and the battery pack cooperates with the corresponding power supply circuit to power the corresponding components in the impact wrench 100. It should be understood by those skilled in the art that the power supply is not limited to the scenario of using a battery pack, and can also be powered by mains electricity, AC power, in conjunction with the corresponding rectification, filtering and voltage regulation circuits to achieve power supply to the corresponding components in the machine. In this embodiment, the DC power supply 30 is specifically configured as a battery pack, and the battery pack 30 will be used to replace the DC power supply hereinafter, but it cannot be used as a limitation to the present application.

[0052] As shown in Figures 1 to 5, 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 a first axis 101. In this embodiment, the motor 12 is specifically configured as an electric motor. Hereinafter, the term "motor" will be used instead of "motor", but this does not limit the present application. In this embodiment, the motor 12 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 12 is an inner rotor brushless motor. In other alternative embodiments, the motor 12 is an outer rotor brushless motor. For inner rotor motors, the stator assembly 122 is mounted on the outside of the rotor assembly 123. For outer rotor motors, the rotor assembly 123 is mounted on the outside of the stator assembly 122. In this embodiment, the brushless motor is configured as a three-phase brushless motor. It is understandable that the motor is not limited to a three-phase brushless motor, and may also be other types of DC motors. The above does not affect the substantive content of this application.

[0053] The housing 11 includes a motor housing 111 configured to accommodate the motor 12 and an output housing 112 that houses at least a portion of the output mechanism 13. The output housing 112 is connected to the front end of the motor housing 111. The housing 11 also forms or is connected to a grip portion 113 for user operation. The grip portion 113 forms a T-shaped or L-shaped structure with the motor housing 111, making it easier for the user to hold and operate the device. A battery pack 30 is connected to one end of the grip portion 113. The battery pack 30 is detachably connected to the grip portion 113.

[0054] The output mechanism 13 includes an output shaft 131 configured to connect to a work accessory and drive the work accessory to rotate. A clamping assembly is provided at the front end of the output shaft 131 to clamp corresponding work accessories, such as a bit, drill bit, sleeve, etc., when performing different functions.

[0055] The output shaft 131 is configured to output power and rotates about the output axis 102. In this embodiment, the first axis 101 and the output axis 102 coincide with each other. In other alternative embodiments, the output axis 102 is arranged at an angle to the first axis 101. In other alternative embodiments, the first axis 101 and the output axis 102 are arranged parallel to each other but do not coincide with each other.

[0056] As shown in Figures 2 to 5, the impact mechanism 15 is configured to provide an impact force to the output shaft 131. The impact mechanism 15 includes a main shaft 151, an impact block 152 sleeved around the outer periphery of the main shaft 151, an anvil 153 disposed at the front end of the impact block 152, and an elastic element 154. The anvil 153 is connected to the output shaft 131. In this embodiment, the anvil 153 includes an anvil seat 1531, and the output shaft 131 is formed or connected to the front end of the anvil seat 1531. It is understood that the anvil seat 1531 and the output shaft 131 may be integrally formed or formed as separate, independent components.

[0057] The impact block 152 is driven to rotate by the drive shaft 121, the anvil 1531 cooperates with the impact block 152 and is struck by it, and the main shaft 151 connects the impact block 152 and the drive shaft 121. In this embodiment, the drive shaft 121 drives the main shaft 151, and the main shaft 151 drives the impact block 152 to rotate.

[0058] The impact block 152 includes an impact block body 1521, and a pair of first end teeth 1523 are radially symmetrically protruded on the front end surface of the impact block body 1521. A pair of second end teeth 1532 are radially symmetrically protruded on the rear end surface of the anvil 1531 opposite to the impact block 152. The output shaft 131 extends out of the output housing 112. The impact block 152 is supported on the main shaft 151 and rotates integrally with the main shaft 151 and can slide back and forth relative to the main shaft 151 in the axial direction of the main shaft. In this embodiment, the axis of the main shaft 151 coincides with the axis of the drive shaft 121, and therefore, the impact block 152 slides back and forth and rotates relative to the main shaft 151 along the direction of the first axis 101. In other alternative embodiments, the axis of the main shaft can be parallel to but not coincide with the axis of the drive shaft 121, or the axis of the main shaft can be set at a certain angle to the axis of the drive shaft 121.

[0059] The elastic element 154 provides a force for the impact block 152 to move closer to the anvil 153. In this embodiment, the elastic element 154 is a coil spring.

[0060] During operation of the impact wrench 100, the impact block 152 rotates integrally with the main shaft 151 while reciprocating back and forth relative to the main shaft 151 along the first axis 101 at a predetermined stroke. A pair of first ball grooves 1522 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 body 1521. A pair of V-shaped second ball grooves 1511 are also formed on the outer surface of the main shaft 151. Both the first ball groove 1522 and the second ball groove 1511 have a semicircular groove bottom. The impact mechanism 15 also includes a rolling ball 155. The rolling ball 155 spans the first ball groove 1522 and the second ball groove 1511, thereby connecting the impact block 152 to the main shaft 151 and moving together. In this embodiment, the rolling ball 155 is a steel ball.

[0061] In the related art, since the impact block and the main shaft are respectively provided with inwardly recessed V-shaped grooves, thereby forming a ball track together, the rolling ball 155 is provided between the impact block 152 and the main shaft 151 and embedded in the ball track, so that the main shaft 151 can drive the impact block 152 to rotate through the rolling ball 155, and the impact block 152 drives the anvil 153 to rotate by cooperating with the anvil 153 to further drive the output shaft 131 to rotate.

[0062] When the impact wrench 100 is unloaded, the impact mechanism 15 does not impact. Instead, it functions as a transmission, transferring 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 impeded. Depending on the load, the output shaft 131 may slow down or stop rotating completely. When the output shaft 131 stops rotating completely, the anvil 153 also stops rotating. Because the anvil 153 limits the impact block 152 circumferentially, the impact block 152 also stops rotating. However, the spindle 151 continues to rotate, forcing the rolling ball 155 to move along the ball path, thereby causing the impact block 152 to move backward along the axis of the spindle 151 and compressing the elastic element 154 until the anvil 153 and impact block 152 are completely disengaged. The spindle 151 drives the impact block 152 to rotate at a certain speed, causing the elastic element 154 to rebound axially. The relative rotational speed between the impact block 152 and the anvil 153 is the rotational speed of the impact block 152. When the impact block 152 rotates until it contacts the anvil 153, it exerts an impact force on the anvil 153. Under the action of this impact force, the output shaft 131 continues to rotate a certain angle to overcome the load, then stops again, and the above process repeats. Because the impact frequency is high enough, a relatively continuous impact force is generated on the output shaft 131, thereby enabling the working accessory to continue to operate.

[0063] As shown in Figures 1 to 3, the impact wrench 100 also includes a main switch 161 and a switching unit 163. The main switch 161 is a trigger switch. The trigger switch is located on the grip 113 for user operation. The rotational speed of the motor 12 is adjusted based on the trigger stroke of the trigger switch. In this embodiment, the trigger switch is coupled to a sliding rheostat 162. Different trigger strokes of the trigger switch result in different analog signals output by the sliding rheostat 162. The trigger stroke of the trigger switch is positively correlated with the duty cycle of the pulse width modulation (PWM) signal of the motor 12, and the duty cycle of the PWM signal is positively correlated with the rotational speed of the motor 12. When the trigger stroke of the trigger switch is small, the duty cycle of the PWM signal is also small, and in this case, the rotational speed of the motor 12 is also small. In some embodiments, the impact wrench stores a mapping relationship between the trigger stroke of the trigger switch and the PWM signal. This mapping relationship can be linear or nonlinear, and is not limited in this embodiment of the present application.

[0064] The switching portion 163 is provided on the upper side of the trigger switch, and is configured to be operated to set the rotation direction of the motor to a forward rotation direction for tightening the fastener or a reverse rotation direction for loosening the fastener.

[0065] 2 to 5 , the transmission mechanism 14 is configured to transmit the torque output by the drive shaft 121 to the output shaft 131. In this embodiment, the transmission mechanism 14 is disposed between the motor 12 and the impact mechanism 15 and is configured to achieve power transmission between the drive shaft 121 and the main shaft 151.

[0066] The transmission mechanism 14 decelerates and increases the output speed and torque of the drive shaft 121, enabling the spindle 151 to drive the impact block 152 to compress the elastic element 154 and move it backward when the load on the output shaft 131 exceeds a threshold. In this embodiment, the nominal voltage of the battery pack 30 is less than 18V. That is, when the motor 12 is powered by the battery pack 30 with a nominal voltage less than 18V, the output shaft 131 of the impact wrench 100 exerts a tightening torque on the workpiece that is greater than or equal to 170N·m. It will be appreciated that the output shaft 131 transmits continuous rotational impacts to the workpiece, generating a tightening torque of at least 170N·m when the battery pack 30 provides a nominal voltage less than 18V to the motor 12. "Tightening torque" refers to torque applied to a fastener in the direction of increasing tension (i.e., tightening). In this embodiment, the transmission mechanism 14 provides a speed ratio from the drive shaft 121 to the main shaft 151 of greater than or equal to 9, so that the output speed of the motor 12, which is adapted to a nominal voltage less than 18V, can be reduced to a speed suitable for the impact mechanism 15 to produce an impact. In this embodiment, the transmission mechanism 14 includes a multi-stage transmission assembly 140 to provide a speed ratio from the drive shaft 121 to the main shaft 151 of greater than or equal to 9. In some embodiments, the nominal voltage of the battery pack 30 is greater than or equal to 3V and less than or equal to 11V. In some embodiments, the nominal voltage of the battery pack 30 is greater than or equal to 3V and less than or equal to 9V.

[0067] According to relevant technology, the output torque of motor 12 is positively correlated with the power of motor 12, and negatively correlated with the output speed of motor 12. The power of motor 12 is the product of the voltage applied to motor 12 and the bus current. Therefore, if the voltage applied to motor 12 is reduced, to achieve the same output torque or output power, the bus current needs to be increased. This is equivalent to compensating for the difference caused by the voltage reduction by increasing the bus current. On the one hand, this increases the cost of the motor 12 itself. On the other hand, since the impact tool uses switching elements (for example, the switching elements include controllable semiconductor power devices (such as field effect transistors (FET), bipolar junction transistors (BJT), insulated gate bipolar transistors (IGBT), etc.), or insulated gate bipolar transistors (IGBT), bipolar junction transistors (BJT), etc.), the motion state of the motor 12 is controlled based on the pulse width modulation (PWM) signal to control the ratio between the on time and the off time of the switching elements. Therefore, when the bus current of the motor 12 is increased, the requirements for the switching elements are also increased, which not only increases the cost during use, but also the requirements for heat dissipation and life. Therefore, in the related art, when the tightening torque of the output shaft 131 on the workpiece is greater than or equal to 170 N·m, the impact tool basically cannot be powered by a battery pack with a nominal voltage less than 18V.

[0068] In the present application, in order to ensure the usability and safety of the components in the motor 12 and its related control circuit, the impact tool uses a battery pack with a nominal voltage less than 18V to power the motor 12, and increases the speed ratio of the transmission mechanism 14 to maintain the output torque, output speed or output power of the motor 12, so that the output torque output by the motor 12 to the impact mechanism 15 is maintained at the original level when the power supply is less than 18V (when the nominal voltage of the power supply battery pack is greater than or equal to 18V). In this embodiment, the speed ratio provided by the transmission mechanism 14 from the drive shaft 121 to the main shaft 151 is greater than or equal to 9. In some embodiments, the speed ratio provided by the transmission mechanism 14 from the drive shaft 121 to the main shaft 151 is greater than or equal to 9.5, 10, 10.5, 11, 11.5, or 12. In some embodiments, the speed ratio provided by the transmission mechanism 14 from the drive shaft 121 to the main shaft 151 is greater than or equal to 12 and less than or equal to 14.

[0069] In this embodiment, the output shaft 131 of the impact wrench 100 has a tightening torque on the workpiece greater than or equal to 170 N·m. In some embodiments, the output shaft 131 of the impact wrench 100 has a tightening torque on the workpiece greater than or equal to 180 N·m. In some embodiments, the output shaft 131 of the impact wrench 100 has a tightening torque on the workpiece greater than or equal to 190 N·m. In some embodiments, the output shaft 131 of the impact wrench 100 has a tightening torque on the workpiece greater than or equal to 200 N·m. In some embodiments, the output shaft 131 of the impact wrench 100 has a tightening torque on the workpiece greater than or equal to 210 N·m and less than or equal to 400 N·m.

[0070] In this embodiment, to ensure the usability and safety of the components in the motor 12 and its associated control circuit, the impact tool uses a battery pack with a nominal voltage of less than 18V to power the motor 12. By increasing the torque output of the transmission mechanism 14, the output torque, output speed, or output power of the motor 12 is maintained. This allows the output torque of the motor 12 to the impact mechanism 15 to remain at its original level when powered by a nominal voltage less than 18V (when the nominal voltage of the power supply battery pack is greater than or equal to 18V). In this embodiment, the transmission mechanism 14 includes a multi-stage transmission assembly 140. Optionally, the multi-stage transmission assembly 140 includes a multi-stage planetary transmission set, for example, the multi-stage transmission assembly 140 includes at least two stages of planetary gear reduction assemblies. The multi-stage transmission deceleration and torque amplification ensure that the transmission mechanism 14 has a larger speed ratio. Compared to using a single-stage transmission assembly, the multi-stage transmission assembly 140 requires lower strength for individual gears to achieve the same speed ratio, which is more beneficial to the life of the transmission components.

[0071] As shown in Figure 4, the transmission mechanism 14 includes a housing assembly 14a, a first-stage planetary gear set 144, and a second-stage planetary gear set 145. It will be appreciated that this embodiment employs two stages of planetary gear sets to minimize the overall length of the impact wrench 100. However, depending on the actual product requirements, the transmission mechanism 14 may include more than two stages of planetary gear sets. This does not affect the substantive content of this application.

[0072] As shown in Figures 2-4, the first-stage planetary gear set 144 and the second-stage planetary gear set 145 are at least partially located within the housing assembly 14a. The first-stage planetary gear set 144 is located near the drive shaft 121, while the second-stage planetary gear set 145 is located near the main shaft 151. The planet carrier of the second-stage planetary gear set 145, the planetary gear set in the multi-stage planetary transmission 140 that is located near the impact mechanism 15, is formed or connected to the main shaft 151. In this embodiment, the speed ratio of the first-stage planetary gear set 144 is greater than 1, and the speed ratio of the second-stage planetary gear set 145 is greater than 1. In some embodiments, the speed ratio of at least one of the first-stage planetary gear set 144 and the second-stage planetary gear set 145 is greater than 1.

[0073] Optionally, the first-stage planetary gear assembly 144 includes: first planetary gears 1441, a first planet carrier 1442 for mounting the first planetary gears 1441, and a first inner ring gear 1443 meshing with the first planetary gears 1441. The drive shaft 121 forms or is connected to a first sun gear 122 that rotates at a first speed. In this embodiment, the first sun gear 122 rotates coaxially with the drive shaft 121. Optionally, the first sun gear 122 rotates about the first axis 101. In other alternative embodiments, the first sun gear 122 is connected to the drive shaft 121.

[0074] The first sun gear 122 drives the first planetary gears 1441. The first planetary gears 1441 mesh with the first sun gear 122. Multiple first planetary gears 1441 are provided, and all of the first planetary gears 1441 mesh with the first sun gear 122. In this embodiment, three first planetary gears 1441 are evenly spaced around the first axis 101.

[0075] The first sun gear 122 and the first planet gears 1441 form a meshing tooth section that transmits power. The addendum diameter of the meshing tooth section of the first sun gear 122 is smaller than the addendum diameter of the first-stage planet gear set 144, so that the number of meshing teeth of the first-stage planet gear set 144 is greater than the number of teeth of the meshing tooth section of the first sun gear 122. In some embodiments, the addendum diameter of the meshing tooth section of the first sun gear 122 is larger than the addendum diameter of the first-stage planet gears 1441. The addendum diameter of the meshing tooth section of the first sun gear 122 is greater than or equal to 8 mm. The addendum diameter of the first planet gears 1441 is less than 8 mm. Optionally, the addendum diameter of the meshing tooth section of the first sun gear 122 is greater than or equal to 9 mm. Optionally, the addendum diameter of the meshing tooth section of the first sun gear 122 is greater than or equal to 10 mm. Optionally, the addendum diameter of the meshing tooth section of the first sun gear 122 is greater than or equal to 11 mm. Optionally, the addendum diameter of the meshing tooth portion of the first sun gear 122 is greater than or equal to 12 mm. Optionally, the addendum diameter of the meshing tooth portion of the first sun gear 122 is 13 mm. Optionally, the addendum diameter of the first planetary gear 1441 is 7.7 mm.

[0076] The first inner ring gear 1443 meshes with the periphery of the plurality of first planetary gears 1441. The first planetary carrier 1442 includes a first transmission disc 1442a, a first support frame 1442b, and a first output portion. The first support frame 1442b and the first output portion are formed on either side of the first transmission disc 1442a. The first output portion rotates synchronously with the first transmission disc 1442a. The first support frame 1442b is inserted into and rotationally connected to the first planetary gears 1441, thereby driving the first planetary carrier 1442 to rotate about the first axis 101. The first output portion is formed with meshing teeth along its circumference and is configured to mesh with the second-stage planetary gear set 145, thereby achieving a transmission connection between the first-stage planetary gear set 144 and the second-stage planetary gear set 145. In this embodiment, the first output portion is the second sun gear 1444 of the second-stage planetary gear set 145.

[0077] The second-stage planetary gear set 145 includes second planetary gears 1451, a second planet carrier 1452 for mounting the second planetary gears 1451, and a second inner ring gear 1453 meshing with the second planetary gears 1451. A second sun gear 1444 drives the second planetary gears 1451. In this embodiment, the second sun gear 1444 rotates coaxially with the drive shaft 121. Alternatively, the second sun gear 1444 rotates about the first axis 101. The second planetary gears 1451 are configured to mesh with the second sun gear 1444. Multiple second planetary gears 1451 are provided, each meshing with the second sun gear 1444. In this embodiment, three second planetary gears 1451 are evenly spaced about the first axis 101. The meshing relationship between the second planetary gears 1451, the second planet carrier 1452, and the second inner ring gear 1453 is similar to that in the first-stage planetary gear set 144 and is well known to those skilled in the art, so this description will not be repeated here.

[0078] The second planetary carrier 1452 includes a second transmission plate 1452a and a second support frame 1452b. The second support frame 1452b is inserted into the second planetary gear 1451 and is rotationally connected to the second planetary gear 1451, so that the second planetary gear 1451 can drive the second transmission plate 1452a to rotate about the first axis 101. In this embodiment, the second transmission plate 1452a is formed at the rear end of the main shaft 151. The second planetary gear 1451 drives the main shaft 151 to rotate via the second planetary carrier 1452. In other alternative embodiments, the second transmission plate 1452a and the main shaft 151 can be independent components, with the second transmission plate 1452a connected to the main shaft 151. As long as the second planetary gear 1451 can drive the main shaft 151 to rotate, it will be sufficient.

[0079] In this embodiment, the ratio of the rotational speed of the drive shaft 121 to the rotational speed of the main shaft 151 is substantially constant. That is, the speed ratio from the drive shaft 121 to the main shaft 151 is substantially constant. Optionally, the first inner ring gear 1443 and the second inner ring gear 1453 are integrally formed components. Optionally, the first inner ring gear 1443 and the second inner ring gear 1453 are the same component, that is, the transmission mechanism 14 includes an inner ring gear 146, which respectively causes the first planetary gear 1441 and the second planetary gear 1451 to perform planetary motion. The inner ring gear 146 not only meshes with the first planetary gear 1441 to perform planetary motion, but also meshes with the second planetary gear 1451 to perform planetary motion. In some alternative embodiments, the first inner ring gear 1443 and the second inner ring gear 1453 are two components, and the first inner ring gear 1443 and the second inner ring gear 1453 do not undergo relative displacement to ensure that the speed ratio is substantially constant.

[0080] It should be noted that the motor 12 , the transmission mechanism 14 , and the impact mechanism 15 may share some structures. Therefore, the present disclosure does not intend to limit the above devices to completely independent parts.

[0081] As shown in Figure 2, along the first axis 101, a first bearing 1512 configured to support the main shaft 151 is located closer to the output shaft 131 than the multi-stage planetary transmission set 140. First bearing 1512 limits axial displacement of the ring gear 146. Optionally, first bearing 1512 partially overlaps with the second planet carrier 1452 along the first axis 101. Optionally, first bearing 1512 does not overlap with the elastic element 154 along the first axis 101. Optionally, first bearing 1512 is disposed within the housing assembly 14a.

[0082] As shown in Figure 6, the motor 12 is a brushless direct current (BLDC) motor. Optionally, the nominal diameter D1 of the stator of the inner rotor brushless direct current motor 12 is less than or equal to 50 mm, for example, the nominal diameter D1 of the stator of the motor 12 is 48 mm. The speed of the motor 12 is greater than or equal to 13,000 RPM and less than or equal to 22,000 RPM. As shown in Figures 5 to 9, a motor front bearing 124 is provided at the front end of the motor 12 to support the rotation of the drive shaft 121. The motor front bearing 124 is positioned in the housing assembly 14a. Among them, the diameter D2 of the motor front bearing 124 is less than or equal to 20 mm, for example, the diameter D2 of the motor front bearing 124 is 16 mm. A positioning protrusion 147 is provided in the housing assembly 14a to limit the axial displacement of the motor front bearing 124, and the diameter D3 of the hole formed by the positioning protrusion 147 is less than or equal to 18 mm, for example, the diameter D3 of the hole formed by the positioning protrusion 147 is 14 mm.

[0083] As shown in Figures 2 and 9, in this embodiment, the diameter D4 of the inner gear ring 146 is less than or equal to 50 mm. Optionally, the diameter D4 of the inner gear ring 146 is less than or equal to 48 mm. Optionally, the diameter D4 of the inner gear ring 146 is less than or equal to 44 mm. Optionally, the diameter D4 of the inner gear ring 146 is less than or equal to 42 mm. Optionally, the diameter D4 of the inner gear ring 146 is less than or equal to 40 mm. In this embodiment, the axial length of the inner gear ring 146 is set to L4, where L4 is the length of the entire inner gear ring. If the inner gear ring is composed of a first inner gear ring and a second inner gear ring, L4 is the total length of the first inner gear ring and the second inner gear ring when fully installed. As shown in Figure 9, if the inner gear ring 146 is a single-piece structure, L4 is the axial length of the inner gear ring 146. In this embodiment, the ratio of the diameter D4 of the inner gear ring 146 to its length L4 is less than or equal to 8.5. In some embodiments, the ratio of the diameter D4 to the length L4 of the inner gear ring 146 is less than or equal to 8, 7.5, 7, 6.5, or 6. This ensures that the transmission mechanism can output a large speed ratio while maintaining a compact radial size and the compactness of the entire machine.

[0084] As shown in FIG6 , in order to enable the impact wrench 100 to output a higher torque, this can be achieved by increasing the mass of the impact block 152 and / or increasing the rotational speed of the impact block 152, so as to provide increased kinetic energy during impact. In this embodiment, the diameter D5 of the impact block 152 is limited to be greater than or equal to 40 mm. Optionally, the diameter D5 of the impact block 152 is 44 mm. Optionally, the mass of the impact block 152 is greater than or equal to 120 g. In some embodiments, the mass of the impact block 152 is greater than or equal to 125 g. The moment of inertia of the impact block 152 is greater than or equal to 35 kg·mm2. The impact block 152 can meet the output torque requirements of the impact wrench 100 and also ensure the compactness of the entire machine. In this embodiment, the diameter D4 of the inner gear ring 146 is smaller than the diameter D5 of the impact block 152. In this embodiment, the impact frequency is greater than or equal to 2500 IPM and less than or equal to 3900 IPM. As defined herein, "impact frequency" refers to the number of impacts applied by the impact block 152 to the anvil 153 per unit time, and IPM stands for Impacts Per Minute. The maximum rotational speed of the output shaft 131 is less than or equal to 3000 RPM. In some embodiments, the maximum rotational speed of the output shaft 131 is less than or equal to 2500 RPM. In some embodiments, the no-load speed of the output shaft 131 is less than or equal to 3000 RPM. In some embodiments, the no-load speed of the output shaft 131 is less than or equal to 2500 RPM. Wherein, the no-load speed is the combined rotation of the spindle 151, the impact block 152, and the anvil 153 during operation of the impact tool in a no-load state, when the output shaft 131 is not configured to apply torque to a workpiece, which defines the "output speed" of the impact tool, which is measured in revolutions per minute.

[0085] As shown in Figures 7 to 9, to ensure radial compactness of the impact wrench 100, a first recess 148 is provided on the outer side of the housing assembly 14a. As shown in Figure 3, the first recess 148 cooperates with the protrusion 1112 on the inner side of the motor housing 111 to limit the circumferential movement of the housing assembly 14a. A second recess 149 is provided on the inner sidewall of the housing assembly 14a, radially outwardly facing the inner sidewall. The second recess 149 cooperates with the limiting protrusion 1461 of the inner ring gear 146 to limit the circumferential movement of the inner ring gear 146. To ensure the overall strength of the housing assembly 14a and mold manufacturability, the second recess 149 is staggered with the first recess 148 to ensure a uniform wall thickness of the housing assembly 14a. Optionally, multiple second recesses 149 are evenly distributed along the circumference, with six second recesses 149 provided within a 360-degree circumference. Multiple first recesses 148 are provided along the circumference. Optionally, two first recesses 148 are provided within a 360° circumference. Optionally, a first recess 148 is provided between two adjacent second recesses 149. Optionally, the first recess 148 and the second recess 149 partially overlap in the radial direction to reduce the radial dimension of the transmission mechanism and thereby ensure the radial dimension of the entire machine.

[0086] As shown in Figures 10 and 11 , regarding the battery pack 30, the nominal voltage of the battery pack 30 is less than 18V. In some embodiments, the nominal voltage of the battery pack 30 is greater than or equal to 3V and less than or equal to 9V. The nominal voltage generally refers to the voltage specified by the manufacturer or seller on the product's label, packaging, user manual, instructions, advertising, marketing, or other supporting documentation to ensure that users understand which power tools and the battery pack 30 are compatible. Alternatively, the nominal voltage of the battery pack 30 can be obtained through detection or calculation. The nominal voltage can be the voltage of the battery pack 30 at fifty percent (50%) of its state of charge (SOC). Optionally, the battery pack 30 includes a battery pack housing 31 and battery cells 32. The voltage of a single battery cell 323 is typically between 3.6V and 4.2V. In this embodiment, the battery pack 30 includes two to five battery cells 323. The battery cells 323 are connected in series, so the nominal voltage of the battery pack 100 can be considered to be between 8V and 18V.

[0087] It is understood that the nominal voltage of the battery pack 30 is related to the number of battery cells 323 connected in series within the battery pack 30. For example, when the number of battery cells 323 within the battery pack 30 is 1, the nominal voltage of the battery pack 30 can be considered to be 3.6V to 4.2V, specifically 3.6V, 4V, or 4.2V.

[0088] In some embodiments, the nominal voltage of the battery pack 30 is greater than or equal to 3 V and less than 18 V. Similarly, when the number of battery cells 323 connected in series within the battery pack 30 is 3, the nominal voltage of the battery pack 30 can be considered to be 10.8 V to 12.6 V, specifically 10.8 V, 12 V, or 12.6 V. Similarly, when the number of battery cells 323 connected in series within the battery pack 30 is 4, the nominal voltage of the battery pack 30 can be considered to be 14.4 V to 16.8 V, specifically 14.4 V, 16 V, or 16.8 V.

[0089] In this embodiment, the nominal voltage of the battery pack 30 is greater than or equal to 7 V and less than or equal to 9 V. For example, in this embodiment, the number of battery cells 323 is two, and two battery cells 323 are connected in series. Therefore, the nominal voltage of the battery pack 30 can be considered to be 7.2 V to 8.4 V, specifically 7.2 V, 8 V, or 8.4 V.

[0090] In some other embodiments, the number of battery cells 323 of the battery pack 30 is less than or equal to 4, and the four battery cells 323 can be connected in series. Alternatively, the four battery cells 323 can also form two battery cell groups, the two battery cell groups are connected in parallel, and the two battery cells 323 in each battery cell group are connected in series. When the four battery cells form two battery cell groups, the nominal voltage of the battery pack 30 can also be considered to be 8V. In some embodiments, the nominal voltage of the battery pack 30 is less than or equal to 9V. In some embodiments, the nominal voltage of the battery pack 30 is greater than or equal to 7V.

[0091] In some embodiments, the nominal voltage of the battery pack 30 is less than or equal to 13 V. For example, the battery pack 30 includes three battery cells 323 connected in series, and the nominal voltage of the battery pack 30 can be 10.8 V, 12 V, or 12.6 V.

[0092] The battery pack 30 can be a lithium battery pack, a solid-state battery pack, or a soft-pack battery pack. The battery pack 30 includes a first portion 33 and a second portion 34. When the battery pack 30 is coupled to the grip 113, the first portion 33 is at least partially disposed within the grip 113, and the second portion 34 is located outside the grip 113. Optionally, the first portion 33 includes a first group of cells, and the second portion 34 includes a second group of cells. For ease of explanation, in this embodiment, the cell units 323 in the first group of cells can also be defined as first cell units 323a, and the cell units 323 in the second group of cells can be defined as second cell units 323b. The first cell units 323a and the second cell units 323b are both pouch-shaped cells. The first cell unit 232a is partially or entirely located within the grip 113, and the second cell unit 232b is located outside the grip 113. The extended plane of the first cell unit 232a is parallel to the first straight line. The extended plane of the second battery cell 232b is perpendicular to the first straight line. The extended plane of the second battery cell 232b is perpendicular to the extended plane of the first battery cell 232a. The battery pack housing 31 is configured to accommodate the first battery cell 232a and the second battery cell 232b. The battery pack housing is generally T-shaped, thereby increasing the capacity of the battery pack 30 while reducing its volume. Alternatively, in some embodiments, the battery pack housing may be generally L-shaped.

[0093] In this embodiment, as shown in FIG1 , the axial length L1 from the rear end of the housing 11 to the front end of the anvil 153 is less than or equal to 145 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the anvil 153 is less than or equal to 140 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the anvil 153 is less than or equal to 135 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the anvil 153 is less than or equal to 125 mm. In this embodiment, because the output shaft 131 and the anvil 153 are integrally formed components and the output shaft 131 is disposed at the front end of the anvil 153, the axial length L1 from the rear end of the housing 11 to the front end of the output shaft 131 is less than or equal to 145 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the output shaft 131 is less than or equal to 140 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the output shaft 131 is less than or equal to 135 mm. In some embodiments, the axial length L1 from the rear end of the housing 11 to the front end of the output shaft 131 is less than or equal to 125 mm. Using a low-nominal-voltage battery pack ensures output torque while maintaining the overall axial length of the impact tool, without affecting the compactness of the entire device, allowing the product to be easily applied in confined working conditions.

[0094] As shown in FIG3 , the impact wrench 100 further includes a lighting assembly 17 . The lighting assembly is configured to illuminate a working area of ​​the impact wrench 100 . The lighting assembly 17 is disposed at a lower portion of the output housing 112 or in an area below the output housing 112 .

[0095] In some alternative embodiments, the lighting assembly is provided on the output housing. Optionally, the lighting assembly includes a plurality of light-emitting bodies arranged circumferentially or in an annular shape along the output shaft 131, and the light-emitting bodies include lamp beads or lamp boards. In some embodiments, the lighting assembly includes lamp beads and a reflector, configured to provide a surface light source. Optionally, the reflector is annular. In some embodiments, the lighting assembly is controlled by a trigger switch. In some embodiments, an independent control and manipulation part is provided to control the lighting assembly. In some embodiments, the working mode of the lighting assembly is adjustable. Among them, the working mode includes brightness, color temperature, delayed lighting time, delayed extinguishing time, constant light or flashing, and other modes that affect the lighting effect.

[0096] The above shows and describes 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 form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of this application.

Claims

1. An impact tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, including an output axis defined by itself, the output shaft rotates around the output axis to output power; the tightening torque of the output shaft on the workpiece is greater than or equal to 170 N·m; An impact mechanism applies an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor and an anvil matched with the impact block and impacted by the impact block; a transmission mechanism configured to transmit the torque output by the drive shaft to the output shaft, wherein the transmission mechanism includes a multi-stage transmission assembly; and A DC power supply is used to supply power to at least the motor, and the nominal voltage of the DC power supply is less than 18V.

2. The impact tool according to claim 1, wherein: The multi-stage transmission assembly includes at least two stages of planetary gear reduction assemblies.

3. The impact tool according to claim 1, wherein: The multi-stage transmission assembly comprises: A first planet carrier is arranged in front of the motor, a first planetary gear supported by the first planet carrier; A second planet carrier, arranged in front of the first planet carrier; a second planetary gear supported by the second planet carrier; and The inner ring gear causes at least the second planetary gear to perform planetary motion.

4. The impact tool according to claim 3, wherein: The outer diameter of the inner gear ring is less than or equal to 50 mm.

5. The impact tool according to claim 3, wherein: The impact mechanism further includes a main shaft connecting the impact block and the driving shaft and a first bearing supporting the main shaft for rotation, wherein the first bearing limits the axial displacement of the inner gear ring.

6. The impact tool according to claim 5, wherein: The first bearing partially overlaps the second planet carrier along the first axis direction.

7. The impact tool according to claim 5, wherein: The ratio of the rotation speed of the driving shaft to the rotation speed of the main shaft is substantially constant.

8. The impact tool according to claim 5, wherein: The speed ratio from the drive shaft to the main shaft is greater than or equal to 9.

9. The impact tool according to claim 3, wherein: The inner ring gear causes the first planetary gear and the second planetary gear to perform planetary motion respectively.

10. The impact tool according to claim 1, wherein The maximum rotation speed of the output shaft is less than or equal to 3000 rpm.

11. The impact tool according to claim 1, wherein The nominal voltage of the DC power supply is greater than or equal to 3V and less than or equal to 9V.

12. The impact tool according to claim 1, further comprising a housing, provided with a housing space, wherein the motor is arranged in the housing space, and a distance L1 from the rear end of the housing to the front end of the output shaft is less than or equal to 145 mm.

13. The impact tool according to claim 12, wherein: The distance L1 from the rear end of the housing to the front end of the output shaft is less than or equal to 135 mm.

14. The impact tool according to claim 1, wherein The transmission mechanism further includes a housing assembly, which includes a first recessed portion disposed on the outside and extending inwardly, and a second recessed portion disposed on the inside and extending outwardly, wherein the first recessed portion and the second recessed portion are circumferentially spaced apart from each other.

15. The impact tool according to claim 1, wherein The diameter of the impact block is greater than or equal to 40 mm, and the mass of the impact block is greater than or equal to 120 g.

16. An impact tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, comprising an output axis defined by itself, wherein the output shaft rotates around the output axis to output power; An impact mechanism applies an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor and an anvil matched with the impact block and impacted by the impact block; A transmission mechanism configured to transmit the torque output by the drive shaft to the output shaft; wherein the tightening torque of the output shaft on the workpiece is greater than or equal to 170 N·m; and A DC power supply is used to supply power to at least the motor, wherein a nominal voltage of the DC power supply is greater than or equal to 3V and less than or equal to 9V.

17. An impact tool comprising: a motor including a drive shaft that rotates about a first axis; An output shaft, comprising an output axis defined by itself, the output shaft rotates around the output axis to output power; wherein the tightening torque of the output shaft on the workpiece is greater than or equal to 170 N·m; an impact mechanism for applying an impact force to the output shaft, the impact mechanism comprising an impact block driven by the motor, an anvil matched with the impact block and impacted by the impact block, and a main shaft connecting the impact block and the drive shaft; a transmission mechanism configured to transmit the torque output by the drive shaft to the main shaft; wherein the speed ratio from the drive shaft to the main shaft is greater than or equal to 9; and A DC power supply is used to supply power to at least the motor, and a nominal voltage of the DC power supply is greater than or equal to 3V and less than or equal to 9V.

18. The impact tool according to claim 17, wherein: The transmission mechanism includes a multi-stage transmission assembly; the multi-stage transmission assembly includes at least two stages of planetary gear reduction assemblies.

19. The impact tool according to claim 17, wherein: The transmission mechanism comprises: A first planet carrier, disposed in front of the motor; a first planetary gear supported by the first planet carrier; A second planet carrier, arranged in front of the first planet carrier; a second planetary gear supported by the second planet carrier; and The inner ring gear causes at least the second planetary gear to perform planetary motion.

20. The impact tool according to claim 17, wherein: The ratio of the rotation speed of the driving shaft to the rotation speed of the main shaft is substantially constant.

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