An electric tool

Abstract

The present application provides a power tool, which has a housing composed of a cylindrical main body and a grip portion. A plurality of components are axially accommodated in the main body. The power tool is characterized in that it includes: a motor serving as a drive source; the motor includes: a rotor assembly and a stator assembly, and the rotor assembly is located inside the stator assembly; the rotor assembly includes a rotating shaft with a cavity inside which rotates synchronously therewith; a speed reduction mechanism, at least part of which is disposed in the cavity of the rotating shaft. The power tool provided by the present invention has a shorter axial length than that of traditional gun drill type power tools, is small in size, compact in structure, light in weight, low in inertia, and is a high-power gun drill. At the same time, the structure of the torque transmission device is greatly simplified, and the transmission efficiency of the system is improved.

Description

Technical Field

[0001] The present invention relates to the field of power tools, and more particularly to a power tool having a cavity inside the rotor. Background Art

[0002] Currently, most traditional gun drill power tools use an inner rotor brushless motor to provide driving power, and a torque transmission device is connected to the output rotating shaft of the inner rotor to meet the requirements of different speeds and torques. For example, a three-stage speed change mechanism (such as, Figure 1 as shown, a three-stage transmission gear) is used to transmit the output torque of a brushless motor (such as three-phase four-pole, three-phase six-pole, etc.) to the output shaft; or a two-stage speed change mechanism is used to transmit the output torque of the brushless motor to the output shaft. In the design of the two-stage or three-stage speed change structure, there are many components and a complex structure in the entire speed change mechanism; there are high requirements for the processing and assembly of each component. In addition, in the design of the two-stage or three-stage speed change structure, there is a problem that it is difficult to shorten the axial dimension. It is not conducive to shortening the axial length of the gun drill, and the efficiency of the entire transmission system is not high.

[0003] With the continuous extension of the application fields of gun drill power tools, it has become an urgent task to promote the technological progress of traditional industries, and the demand for developing a gun drill with a small size, compact structure, light weight, low inertia, and high power has become increasingly prominent. Summary of the Invention

[0004] To solve the deficiencies of the prior art, one of the objectives of the present invention is to provide a gun drill with a small size, compact structure, light weight, low inertia, and high power, and at the same time simplify the speed change structure while meeting the requirements of speed and torque.

[0005] To achieve the above objective, the present invention adopts the following technical solutions:

[0006] A power tool includes a housing composed of a cylindrical main body and a handle portion, and a plurality of components are axially accommodated in the main body, including: a motor serving as a driving source; the motor includes: a rotor assembly and a stator assembly; the rotor assembly is located inside the stator assembly; the rotor assembly includes a rotating shaft having an accommodation cavity inside and rotating synchronously therewith, and the axial length of the rotating shaft is longer than the axial length of the stator assembly; a connecting portion is disposed on the inner surface of one end of the rotating shaft protruding from the stator assembly for fixedly connecting with a chuck or an output spindle.

[0007] Preferably, the rotating shaft includes: a rotating shaft main body axially located within the contour of the stator assembly; a protruding portion protruding from the stator assembly and connected to the rotor main body through a transition portion; the radial diameter of the protruding portion is 0.3 to 0.1 times the radial diameter of the rotating shaft main body.

[0008] Preferably, a connecting portion is disposed inside the protruding portion, and the connecting portion includes a thread for fixedly connecting to a chuck or an output spindle.

[0009] Preferably, the power tool includes a control circuit, and the control circuit includes a microcontroller, a detection module, and a control module; the detection module can detect motor parameters and output detection signals to the microcontroller; the control module is electrically connected to the microcontroller and is used to change the direction of the motor current according to the signal of the microcontroller, control the forward or reverse rotation of the motor, and control the rotation speed of the motor.

[0010] An embodiment of the present invention further provides a power tool, which has a housing composed of a cylindrical main body and a handle portion, and a plurality of components are axially received in the main body, including: a motor serving as a drive source; the motor includes: a rotor assembly and a stator assembly, and the rotor assembly is located inside the stator assembly; the rotor assembly includes a rotating shaft with a cavity inside that rotates synchronously therewith; a reduction mechanism, at least partially disposed in the cavity of the rotating shaft.

[0011] Preferably, the rotor assembly is located within the contour of the stator assembly.

[0012] Preferably, the reduction mechanism includes a sun gear disposed in the cavity of the rotating shaft and rotating synchronously with the rotating shaft.

[0013] Preferably, the rotor assembly includes a first support portion disposed in the cavity and located within the contour of the stator assembly.

[0014] Preferably, the first support portion is substantially perpendicular to the axis direction of the rotating shaft, and one side of the center portion of the first support portion includes a fixing portion for connecting the sun gear.

[0015] Preferably, the other side of the center portion of the first support portion includes a first fixing portion for connecting a support bearing.

[0016] Preferably, the support bearing is fixedly connected to the first fixing portion, and the support bearing is disposed in the cavity.

[0017] Preferably, the sun gear is a sun gear, and the reduction mechanism further includes a plurality of planetary gears; the plurality of planetary gears are respectively fixed to a planet carrier through carrier pins, and the plurality of planetary gears are evenly arranged circumferentially along the planet carrier; the plurality of planetary gears are respectively meshed with the sun gear; torque is transmitted between the sun gear and the planet carrier through the meshing of the planetary gears.

[0018] Preferably, the radial contour of the planet carrier is located within the radial contour of the rotating shaft.

[0019] Preferably, the power tool includes a needle bearing disposed between the inner side of the rotating shaft and the outer side of the planet carrier; and an internal gear ring disposed inside the planet carrier and meshing with a plurality of the planet gears.

[0020] Preferably, the internal gear ring is fixedly coupled or integrally formed with the main shaft locking disc.

[0021] Preferably, it includes an output main shaft, one side of the planet carrier is connected to the output main shaft for receiving the rotational torque of the reduction mechanism; and a torque adjustment unit, one side of the torque adjustment unit is connected to the output main shaft, and the other side of the torque adjustment unit is connected to the chuck.

[0022] Preferably, it includes a clutch device disposed between the planet carrier and the output shaft.

[0023] Preferably, the reduction ratio of the reduction mechanism is between 3 and 10.

[0024] Preferably, the reduction ratio of the reduction mechanism is between 4 and 6.

[0025] Preferably, the radial profile of the reduction mechanism is within the radial profile of the motor.

[0026] Preferably, the power tool includes a control circuit, which includes a microcontroller, a detection module, and a control module; the detection module can detect motor parameters and output detection signals to the microcontroller; the control module is electrically connected to the microcontroller and is used to change the direction of the motor current according to the signal of the microcontroller, control the forward or reverse rotation of the motor, and control the rotation speed of the motor.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] The axial length of the power tool proposed by the present invention is shorter than that of the traditional gun drill type power tool, with a small size, compact structure, light weight, low inertia, and high power gun drill. At the same time, the structure of the torque transmission device is greatly simplified, improving the transmission efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a structural schematic diagram of a prior art traditional gun drill power tool;

[0030] Figure 2 is a schematic diagram of a power tool according to an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of a power tool according to an embodiment of the present invention;

[0032] Figure 4 is Figure 3 a partially enlarged schematic diagram;

[0033] Figure 5 Schematic diagram of an electric motor according to an embodiment of the present invention. Specific embodiments

[0034] In order to make the above objects, features, and advantages of the present invention more apparent and understandable, the following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0035] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element present or it may be electrically connected to the other element.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] The structures, shapes, etc. of various mechanisms mentioned in the following embodiments are not limited to the described embodiments, and various simple and well-known substitutions can be made. For example, the housing can be integrally formed with the middle cover, the front housing, etc. In addition, in other embodiments, the power tool can only implement three functions, such as a combination of an electric screwdriver, an impact wrench, and an electric drill. In this case, only the vibration mechanism and the vibration switching member need to be omitted accordingly, or a combination of an impact wrench, an electric drill, and an impact drill. In this case, only the pressing mechanism needs to be omitted accordingly. In addition, in other embodiments, if high and low speed switching is not required, the speed switching mechanism can also be omitted accordingly.

[0038] A power tool according to an embodiment of the present invention; it includes: a main body housing and a handle portion connected to the base end portion of the main body housing.

[0039] Among them, inside the main body housing, there are operating components configured; the operating components sequentially include a power device (such as: a motor, also known as a motor); (in some embodiments, there is also included) a speed reduction device (such as a speed reduction mechanism), (in some embodiments, there is also included) a clutch device (such as a clutch), a working shaft (also known as an output shaft, an output main shaft), and a tool chuck sleeved on the front end of the working shaft. The tool chuck is used to respectively hold different working heads when the power tool realizes different functions. For example, when realizing the function of an impact wrench, it holds a fastening head; when realizing the function of an electric drill, it holds a construction drill, and when realizing the function of an impact drill, it holds a twist drill, and when realizing the function of an electric screwdriver, it holds a screwdriver bit.

[0040] The handle part is the part that the user holds when using the power tool. Usually, two semi-cylindrical handle pieces are combined to form a cylindrical shape (or designed to conform to the shape of the hand). Inside the handle part, there is a control module configured to control the power tool to operate according to a set mode. There is a button switch provided on the handle part to control the start and stop of the power tool; one end of the handle part is detachably plugged with a battery pack. The MAX voltage of the battery pack can be 12V (connection type: such as 3S1P, 3S2P, etc.), 16V, 20V, 24V, etc. (the connection type is the same as that of 12V, and will not be repeated here). The specific voltage can depend on the application scenario of the power tool and is not limited here. The battery chip inside the battery pack can select lithium batteries, fuel cells, etc. The battery pack can be installed in the installation port of the handle part of the power tool in a pluggable manner (such as a snap structure).

[0041] In one embodiment, the power tool does not use a battery pack and uses an AC power supply as the input power supply. At this time, there is a wiring port for connecting the power supply (the power supply connection line is matched and connected to this port to provide driving power for the power tool) or a power supply connection line provided at the end of the handle part.

[0042] In one embodiment, the motor uses an inner rotor type motor. Looking at it from the cross-section, it is roughly arranged in a ring shape. It includes a stator assembly and a rotor assembly, and the rotor assembly is located inside the stator assembly. After the motor is powered on and started, the inner ring rotor assembly rotates at a high speed under the action of electromagnetic induction. There is a cavity inside the rotor assembly (that is, a hollow structure is adopted). Under the condition that the power P of the motor (power P = T * N, T represents torque, unit: N·m; N represents rotational speed, unit: revolutions per minute) is the same, the diameter of the rotor assembly of the motor adopting this structure is slightly larger than that of the rotor of a traditional brushless motor. In this way, the torque requirement can be met even at a lower rotational speed. The rotational speed of a traditional gun drill type motor is high (usually above 10,000 revolutions per minute, and even above 20,000 revolutions per minute) to increase the power density. While the rotational speed of the motor in this embodiment is lower than that of the traditional gun drill type motor, and its rotational speed is roughly above 6,000 revolutions per minute.

[0043] Next, in combination with Figure 2 、3 The embodiments of the present invention will be described in detail with reference to FIGS. 4 and 5.

[0044] Please refer to Figure 2 , which is a schematic structural view of a power tool according to an embodiment of the present invention.

[0045] A power tool 200 includes: a cylindrical main body 201 (also referred to as "main body housing"), a grip portion 202 connected to the base end portion of the main body housing, and a plurality of components are axially received in the cylindrical main body 201; including:

[0046] A motor 203 is disposed in the cylindrical main body, and its output rotational power serves as a driving source;

[0047] The motor includes: a stator assembly 203a and a rotor assembly;

[0048] The rotor assembly is located inside the stator assembly 203a. The rotor assembly 203b includes a rotating shaft 203b having an accommodation cavity therein that rotates synchronously therewith. The axial length of the rotating shaft 203b is longer than the axial length of the stator assembly; wherein; a connecting portion is disposed on the inner surface of the protruding portion 204d at one end of the rotating shaft protruding from the motor.

[0049] An output shaft 204, one end of which is connected to the connecting portion and the other end is connected to a chuck 205.

[0050] In the above embodiment, for convenience of description, the rotating shaft of the rotor assembly is denoted as 203b (of course, the rotor assembly also includes components such as coils). The axial length of the rotating shaft is 1.5 to 10 times the axial length of the stator assembly. Preferably, the axial length of the rotating shaft is 1.5 to 5 times the axial length of the stator assembly. If the axial length of the rotating shaft is too long (for example, exceeding 10 times), on the one hand, it is not conducive to shortening the axial dimension of the power tool motor, and on the other hand, it reduces the strength of the rotating shaft. A connecting portion is disposed on the inner surface of one end (also referred to as the protruding end) of the rotating shaft protruding from the motor for connecting the output shaft or directly connecting the chuck.

[0051] In the above-described embodiments, the rotor assembly is located inside the stator assembly 203a. The rotor assembly includes a rotating shaft 203b that rotates synchronously therewith and has an accommodation cavity inside. One end of the rotating shaft is fixed to the first support portion by a first support bearing 209a; the other end is fixed to the second support portion by a second support bearing 209b. The other end protrudes from the stator assembly (or the motor), and a connecting portion is disposed on the inner surface of the end protruding from the motor for connecting to the output shaft 204. Preferably, the connecting portion connects to the output shaft 204 through a locking chuck, and the torque of the motor 203 is transmitted to the chuck 205 through the output shaft 204. Preferably, it further includes an internal gear ring 210, which is integrated with the locking chuck (the internal gear ring 210 is integrally designed with the locking disk of the output main shaft locking clutch, improving the assembly accuracy and system stability compared with the separate design of traditional power tools. Sometimes, it can also be designed that the internal gear ring 210 is fixedly engaged with the locking disk of the output main shaft locking clutch) and integrated with the locking chuck. One end of the output shaft 204 is fixed to the third support portion by a third support bearing 204a, and the other end is fixed to the fourth support portion by a fourth support bearing 204b. The axial length of the rotating shaft 203b is 1.2 to 10 times the axial length of the stator assembly. Preferably, the axial length of the rotating shaft is 1.5 to 5 times the axial length of the stator assembly. The diameter of the end of the rotating shaft protruding from the motor is about 0.3 to 0.95 times the diameter of the other end. The thickness (D1) of the end of the rotating shaft protruding from the motor is larger than the thickness (D2) of the main body portion of the rotating shaft. Preferably, D1≥1.5*D2 is selected. Preferably, D1≥2.0*D2 is selected. The advantages of such selection are as follows: 1. Improve the connection strength with the main shaft; 2. Facilitate the design of the structure of the connecting portion.

[0052] In the above-described embodiments, the rotating shaft 203b includes a rotating shaft main body (whose axis is generally located within the contour of the stator assembly) and a protruding portion 203d (the portion of the rotating shaft protruding from the motor). The rotating shaft main body is connected to the protruding portion 203d through a transition portion 203c (preferably, integrally formed); the diameter of the protruding portion 203d is about 0.3 to 0.1 times the diameter of the rotating shaft main body. Preferably, 0.5 to 0.8 times is selected (the protruding portion is located within the contour of the rotating shaft main body). The thickness (D1) of the protruding portion 203d of the rotating shaft is larger than the thickness (D2) of the main body portion of the rotating shaft. Preferably, D1≥1.5*D2 is selected. Preferably, D1≥2.0*D2 is selected. Preferably, the cavity inside the rotating shaft main body is communicated with the cavity inside the protruding portion 203d, which is conducive to heat dissipation.

[0053] In the concept of the above-described embodiment, the rotating shaft of the motor included in the power tool is connected to the chuck through a connecting portion (i.e., there is no speed reduction mechanism between the motor and the chuck). This solution has a simple structure, light weight, low inertia, and high efficiency of the system. The speed of the motor is low (lower than the speed of the motor of a traditional gun drill), and the vibration and noise are much lower than those of similar traditional gun drill tools.

[0054] In one embodiment, the connecting portion is configured with a thread and is fixedly connected to the chuck through this thread.

[0055] In one embodiment, the connecting portion is configured with a square bayonet or other types of bayonets and is fixedly connected to the chuck.

[0056] In one embodiment, a torque adjustment device is arranged between the output shaft and the chuck.

[0057] In one embodiment, the power tool has no output shaft, that is, one end of the rotating shaft protruding from the motor (with a connecting portion arranged on the inner surface) is connected to the chuck.

[0058] In one embodiment, the power tool further includes a control circuit, which is arranged in the handle portion (or at least partially arranged in the handle portion). The control circuit includes a microcontroller, a detection module, and a control module. Among them, the detection module is electrically connected to the microcontroller to detect motor parameters and output detection signals to the microcontroller. The control module is electrically connected to the microcontroller to change the operation of the motor according to the signal of the microcontroller. For example, it can change the direction of the motor current, control the forward or reverse rotation of the motor, control the speed of the motor, stop the machine, etc.

[0059] In one embodiment, the main body housing 201 or the handle portion 202 of the power tool is provided with a speed selection switch (a first speed mode (low speed), a second speed mode (high speed), and the user selects the speed according to the actual usage scenario of the tool). One end of the handle portion is detachably plugged with a battery pack 206. The type of the battery pack is the same as above and will not be described repeatedly here.

[0060] In one embodiment, the handle portion 202 is the part that the user holds when using the power tool 200. It is formed into a cylindrical shape by combining two semi-cylindrical handle pieces together (or designed to conform to the shape of the hand). The control module is arranged inside the handle portion 202 to control the power tool to operate according to the set mode (such as forward rotation, reverse rotation) according to the forward and reverse switch 208. A button switch 207 is provided on the handle portion to control the start and stop of the power tool (in one embodiment, this switch is designed as a stepless speed change type switch, that is, the speed of the motor is adjusted according to the depth of the user pressing the switch); one end of the handle portion is detachably plugged with a battery pack 206. The type of the battery pack is the same as above and will not be described repeatedly here.

[0061] Please refer to Figure 3, is a schematic structural view of a power tool 300 according to an embodiment of the present invention. The main difference from the power tool 200 shown in Figure 2 is that it includes a speed reduction mechanism (speed reduction box). Figure 4 is Figure 3 a partial enlarged view. Next, the power tool of the embodiment will be described in detail with reference to Figure 3 and Figure 4 The power tool includes: a housing having a cylindrical main body 301 (also referred to as the "main body housing") and a grip portion 302 (the grip portion 302 is connected to the base end portion of the outer shell of the cylindrical main body 301), and a plurality of components are axially received in the cylindrical main body 301; including: a motor 303 serving as a drive source, the motor 303 includes: a stator assembly 303a, a rotor assembly 303b; the rotor assembly 303b is located inside the stator assembly 303a; the rotor assembly 303b includes a rotating shaft having a cavity (accommodation) inside and rotating synchronously therewith;

[0062] a speed reduction mechanism 313, at least part of which is disposed in the cavity of the rotating shaft (the speed reduction mechanism is connected to the rotating shaft);

[0063] The (drive) gear 313a of the speed reduction mechanism 313 is disposed in the cavity of the rotor assembly 303b and rotates coaxially with the rotor assembly 303b. The planet gear 313b of the speed reduction mechanism 313 is fixed to the planet carrier 311;

[0064] One end of the output main shaft 304 is connected to the planet carrier 311, and the other end is connected to the chuck 305 to receive and transmit the rotational torque. According to the idea of the embodiment, the power tool includes an inner rotor type motor (motor), the inside of the rotor includes a hollow cavity, and part of the speed reduction box is accommodated in the cavity (in this way, the size in the axial direction of the motor can be reduced, which is beneficial to optimizing the size of the power tool). Specifically, the power tool includes a sun gear fixedly connected to the inner ring rotor (which can also be an integrally formed design), and the sun gear is fixedly installed at the hollow (cavity) position of the motor through a support bearing; a planet carrier is provided in front of the sun gear, and the torque is transmitted between the sun gear and the planet carrier through the planetary gear (planet gear); an output main shaft is provided in front of the planet carrier, and the output shaft receives the rotational torque of the planet carrier. Specifically, the rotational torque from the sun gear and the planet carrier is received through a main shaft locking clutch located between the planet carrier and the output main shaft. An internal gear ring is provided outside the planet carrier to seal and encapsulate components such as the sun gear, planet gear, planet carrier, and main shaft locking clutch. Preferably, the output main shaft is fixedly installed on the housing through two support bearings.

[0065] In the above-described embodiments, the power tool generally has a gun-shaped layout, with a driving axis X arranged horizontally and a handle axis Y arranged at a substantially perpendicular angle to the horizontal axis X. Along the horizontal axis X, a (drill) chuck 305 is connected at the frontmost position (the right side in the figure is the front) for mounting and fixing a drill bit or a screwdriver bit (not shown in the figure). The motor 303, the reduction mechanism 313, and the output main shaft 304 are connected in sequence, where the output main shaft is connected to the chuck 305; the motor 303 is coaxially connected (rotated) with the reduction mechanism 313. The reduction mechanism 313 includes: a sun gear 313a and a planetary gear assembly 313b; the sun gear 313a (sun wheel) is arranged in the cavity of the rotor assembly 303b of the motor 303. The planetary gears 313b (the number of planetary gears is set according to the application and can be 2, 3, 4 or more) are fixed to the planet carrier 311 through carrier pins 314. The planetary gears 313b mesh with the sun gear 313a to transmit the torque of the motor 303. The radial profile of the planet carrier 311 is located within the radial profile of the rotor assembly 303b. One side of the planet carrier 311 is movably connected to one end of the output main shaft locking clutch dial 312, and the other end of the clutch dial 312 is connected to one end of the output main shaft 304, and the other end of the output main shaft 304 is connected to the chuck 305. The reduction mechanism 313 further includes an internal gear ring 310, which is arranged outside the planet carrier 311 to seal and encapsulate components such as the sun gear 313a, the planetary gears 313b, the planet carrier 311, and the main shaft locking clutch 312 (i.e., components such as the sun gear, the planetary gears, the planet carrier, and the main shaft locking clutch are included in the cavity of the internal gear ring). A second support bearing 309b (preferably, a needle bearing is selected) is arranged between the internal gear ring 310 and the rotor assembly 303b. When the motor 303 rotates, the second support bearing 309b cooperates with the first support bearing 309a to ensure the coaxial rotation of the reduction mechanism 313 and the motor 303. When the reduction mechanism 313 rotates, the teeth inside the internal gear ring 310 mesh with the planetary gears 313b. Along the handle axis Y (also called the handle), a battery pack 306 is installed at one end of the handle to supply power to the motor 303. A control switch 307 is also arranged on the handle to control the opening or closing of the motor 303. In one embodiment, the rotor assembly 303b is integrally provided with a rotating shaft. In one embodiment, in addition to the function of controlling the opening or closing of the motor, the control switch also has a speed regulation function (by pressing the control switch, that is, within the designed stroke, when the control switch is in different positions, the rotational speed of the motor is different, that is, stepless speed regulation). Or the handle is provided with a speed selection switch, and the detailed configuration is the same as above and will not be repeated here. In one embodiment, the power tool further includes a forward and reverse switch 308 for controlling the forward and reverse rotation of the motor. In this embodiment, multiple components are axially connected in parallel and housed inside the cylindrical main body.

[0066] In the above-described embodiments, torque is transmitted between the sun gear 313a and the planet carrier 311 through the meshing of the planet gears 313b. The sun gear 313a (sun gear) of the speed reduction mechanism 313 is disposed within the cavity of the rotor assembly 303b. The rotational speed of the motor 303 is reduced by the speed reduction mechanism 313 and adjusted to the desired rotational speed, which is then transmitted to the output main shaft 304 and the chuck 305.

[0067] In the above-described embodiments, the internal gear ring rotates coaxially with the planet carrier. The internal gear ring has a rotatable state in which it can be rotationally driven when the load on the working shaft reaches a preset value, and a restricted rotation state in which it cannot be rotationally driven regardless of the magnitude of the load on the working shaft. The contour of the internal gear ring is within the contour of the motor. Preferably, it is within the contour of the rotor assembly. In one embodiment, the contour of the speed reduction mechanism is within the contour of the motor. In one embodiment, the radial contour of the speed reduction mechanism is within the radial contour of the motor.

[0068] In the above-described embodiments, the output main shaft 304 is fixedly installed within the main body housing through the third support bearing 304a and the fourth support bearing 304b.

[0069] In the above-described embodiments, the speed reduction mechanism 313 is connected (rotates) coaxially with the rotating shaft of the motor 303.

[0070] In one embodiment, as Figure 5 shown, it is a schematic diagram of the connection between the rotor assembly and the sun gear of the speed reduction mechanism; the rotor assembly 403b is located inside the stator assembly 403a; the rotor assembly 403b includes a first support portion 403c. On one side of the central portion (axis region) of the first support portion 403c, a first fixing portion 403e is disposed, and the first fixing portion 403e is used to fix the sun gear 413a; on the other side of the central portion (axis region) of the first support portion 403c, a second fixing portion 403f is disposed, and the second fixing portion 403f is used to fix the first support bearing 409a; a rotating shaft 403d, and the first support portion 403c is substantially perpendicular to the axis direction of the rotating shaft 403d of the rotor assembly 403b. The sun gear 413a (sun gear) is installed on the first fixing portion 403e. In this embodiment, the first support portion 403c, the first fixing portion 403e, and the second fixing portion 403f are integrally formed. Preferably, the first support portion 403c, the first fixing portion 403e, the second fixing portion 403f, and the rotating shaft of the rotor assembly 403b are integrally formed. Preferably, after fixation, the first support bearing 409a is located within the cavity contour of the rotor assembly 403b.

[0071] In one embodiment, the rotor assembly 403b and the rotating shaft it includes are integrally designed, and sometimes the rotating shaft is described using the rotor assembly.

[0072] In one embodiment, the first support portion roughly divides the axially rotating accommodation cavity of the rotor assembly 403b into two cavities (a first cavity, which contains: a first support bearing; a second cavity, which contains: a sun gear). In this embodiment, the reduction ratio of the reduction mechanism is between 3 and 10. Preferably, the reduction ratio of the reduction mechanism is between 4 and 6. In this way, under the same adjustment of the motor power, the power tool using the motor of the above embodiment can meet the performance requirements of the traditional power tool using a three-stage reduction mechanism.

[0073] In one embodiment, when there are multiple planetary gears (also known as planet gears), they are respectively fixed to the planet carrier through load-bearing pins, and the planetary gears are evenly arranged circumferentially along the planet carrier; the multiple planetary gears are respectively meshed with the sun gear to transmit torque.

[0074] In one embodiment, the position of the first support portion is in the middle region of the axial direction of the rotating shaft or near the rear cover region (the side opposite to the chuck direction).

[0075] In one embodiment, the gears of the reduction mechanism are arranged in the cavity of the rotating shaft and rotate synchronously with the rotating shaft.

[0076] In one embodiment, the power tool further includes a torque adjustment unit, which is installed between the output main shaft and the chuck. One side of the torque adjustment unit is connected to the output main shaft, and the other side is connected to the chuck to receive and transmit the rotational torque.

[0077] In one embodiment, the power tool includes a clutch device, and the clutch device is arranged between the planet carrier and the output main shaft. Preferably, the clutch device is integrally pluggable with the planet carrier. Preferably, the clutch device includes a clutch pull plate for locking the main shaft.

[0078] In one embodiment, in the axial direction of the motor, the length of the rotor assembly is less than the length of the stator assembly.

[0079] In one embodiment, the power tool further includes a control circuit, which is arranged in the handle portion and includes a microcontroller, a detection module, and a control module; the detection module can detect motor parameters and output detection signals to the microcontroller; the control module is electrically connected to the microcontroller and is used to change the direction of the motor current according to the signal of the microcontroller, control the forward or reverse rotation of the motor, and control the rotation speed of the motor.

[0080] It should be noted that in one embodiment, for a power tool, among the features such as "motor", "rotor assembly", "speed reduction mechanism", "internal gear ring", "rotating shaft", "torque adjustment unit", "control circuit", "control switch", "output main shaft", "battery pack", etc., only one or more of these technical features may be included. Among them, the content regarding the "motor" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "rotor assembly" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "speed reduction mechanism" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "internal gear ring" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "rotating shaft" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "torque adjustment unit" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "control circuit" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "control switch" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "output main shaft" can be selected from one or a combination of those containing its related technical features in the embodiment; the content regarding the "battery pack" can be selected from one or a combination of those containing its related technical features in the embodiment.

[0081] In the design of the power tool, the power tool adopts an inner rotor type motor, and the interior of the rotor assembly contains an accommodation cavity. It can be designed as a mechanism directly connecting the chuck, that is, the rotating shaft of the rotor assembly protrudes from the stator assembly, and the protruding end is fixedly connected to the chuck. With such a design, the axial length of the motor is better optimized, and the designed power tool has the characteristics of low inertia and low noise, improving the user experience.

[0082] In the design of the power tool with a primary speed reduction mechanism, in the axial length of the motor, the length of the rotor assembly is less than the length of the stator assembly. The reduction ratio is between 3 and 10. Preferably, the reduction ratio is between 4 and 6. With such a design, the power tool has the characteristics of low inertia and low noise, improving the user experience.

[0083] In the design of the power tool, the main body housing or the grip part can be integrally formed, and when manufacturing, the integrally formed main body housing or grip part is divided into two parts and injection molded separately.

[0084] In the design of the motor, an inner-rotor type is adopted, and a hollow cavity (accommodating cavity) is included inside the rotor assembly. The rotational speed of the motor is much lower than that of a traditional gun drill and meets the requirements of rotational speed and torque in applications. When in use, it has low inertia, low noise, high precision, can work continuously, and has a large temperature rise margin of the motor, improving the user experience.

[0085] In the design of the rotor assembly, the rotor assembly includes a rotating shaft with an accommodating cavity inside that rotates synchronously with it; one end of the rotating shaft is fixed to the supporting part through a first supporting bearing, and the other end protrudes from the motor. A connecting part is arranged on the inner surface of the end protruding from the motor for connecting the output shaft. Preferably, the connecting part connects the output shaft through a locking chuck. The torque of the motor is transmitted to the chuck through the output shaft. Preferably, the axial length of the rotating shaft is 1.2 to 10 times the axial length of the stator assembly. Preferably, the axial length of the rotating shaft is 1.5 to 5 times the axial length of the stator assembly.

[0086] In the design of the rotating shaft, the rotating shaft includes a rotating shaft main body (whose axis is generally located within the contour of the stator assembly) and a protruding part (the part of the rotating shaft protruding from the motor). The rotating shaft main body is connected to the protruding part through a transition part 203c (preferably, integrally formed); the diameter of the protruding part is about 0.3 to 0.1 times the diameter of the rotating shaft main body. Preferably, 0.5 to 0.8 times is selected (the protruding part is located within the contour of the rotating shaft main body). The thickness (D1) of the protruding part of the rotating shaft is larger than the thickness (D2) of the rotating shaft main body part. Preferably, D1≥1.5*D2 is selected. Preferably, D1≥2.0*D2 is selected. Preferably, the cavity inside the rotating shaft main body is communicated with the cavity inside the protruding part, which is conducive to heat dissipation.

[0087] In the design of the internal gear ring, the internal gear ring is integrally designed with the locking disc of the output main shaft locking clutch, improving the assembly precision and system stability compared with the separate design of traditional power tools.

[0088] In the design of the rotor assembly, a hollow cavity is included inside the rotor assembly of the motor. When cooperating with a first-stage reduction mechanism, the sun gear (also called sun gear, also called driving gear) of the reduction mechanism is installed in this cavity; the sun gear is inside the rotor contour, and from the side view, the contour of the reduction structure is inside the motor contour. Such a design makes the axial dimension of the power tool shorter than that of a traditional gun drill and has a simple structure at the same time.

[0089] In the design of the speed reduction mechanism, the sun gear (also known as the sun gear and the driving gear) of the speed reduction mechanism is installed in the cavity of the rotor assembly. The sun gear is inside the rotor profile, and from the side view, the profile of the speed reduction structure is within the profile of the motor. In the design of the speed reduction mechanism, a single-stage speed reduction design is adopted, that is, the sun gear meshes with a set of planetary gears. Such a design makes the axial dimension of the power tool shorter than that of the traditional gun drill, and at the same time, the structure is simple. It improves the overall reliability of the power tool.

[0090] In the design of the switch, in addition to the function of controlling the motor to start or stop, the switch also has the function of stepless speed regulation.

[0091] In the design of the control switch, in one embodiment, the main body housing or the handle part of the power tool is provided with a speed selection switch, and the user can select the low-speed mode or the high-speed mode according to the actual use scenario of the tool.

[0092] In the design of the control circuit, at least part of the control circuit is arranged in the handle part, including a microcontroller, a detection module, and a control module; the detection module can detect the motor parameters and output a detection signal to the microcontroller; the control module is electrically connected to the microcontroller, and is used to change the direction of the motor current according to the signal of the microcontroller, control the forward or reverse rotation of the motor, and control the rotation speed of the motor.

[0093] In the design of the battery pack, the MAX voltage of the battery pack can be 12V, 16V, 20V, 24V, etc. The specific voltage can be determined according to the application scenario of the power tool and is not limited here. The battery chip inside the battery pack can be a lithium battery, a fuel cell, etc.

[0094] The output shaft mentioned in the above embodiments is also called the output main shaft.

[0095] In the above-described embodiments, the power tool may be a gun drill type tool, which can achieve functions such as electric drill function, electric screwdriver function, and so on. An electric drill is used to drill holes in a workpiece. During the operation, the drill output shaft continuously rotates to drive the drill bit to perform a rotational motion. An electric screwdriver is used to tighten a screw onto a workpiece. It usually includes a clutch structure, which is composed of a clutch driving member and a driven member. The driving member is integrated with the reduction gear, while the driven member rotates and is fixed within the housing and can axially move relative to the housing. The working spring acts on the end face teeth of the driving member through the driven member, so that the driving member is fixed in the rotational direction and can transmit torque to make the screwdriver rotate. During the operation, the torque of the motor is transmitted to the chuck through the planetary gear reduction mechanism to make it rotate. For example, the screwdriver bit and the screw head groove cooperate, so that the screw is quickly tightened. As the screw is tightened, the resistance torque on the driving member rapidly increases, and an axial thrust is generated through the end teeth. When the resistance torque exceeds the tripping preset value, the axial thrust forces the driven member to further compress the working spring and disengage from the driving member. When the driving member loses the support of the driven member, it is rotationally driven, so that the planetary gear reduction mechanism has no output. The driving member still has a tendency to rotate with the motor output shaft, and then meshes again under the restoring force of the working spring. This cycle repeats, the screw no longer receives torque, and the motor is still rotating. Through this structure, the tightened screw reaches the specified tensile force and will not be pulled apart, and the motor will not be overloaded, stalled, damaged, or burned out.

[0096] That is to say, the above features can be arbitrarily arranged and combined and used for the improvement of the power tool.

[0097] The above-described embodiments only express several embodiments of the present invention. Due to the limited nature of the written expression, there are objectively infinite possible structures. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. An electric tool includes a housing composed of a cylindrical main body and a grip portion, and a plurality of components are axially accommodated in the main body. Characterized in that: It includes: A motor serving as a drive source; The motor includes a rotor assembly and a stator assembly; the rotor assembly is located inside the stator assembly; the rotor assembly includes a rotating shaft with an accommodation cavity inside, which rotates synchronously therewith, and the axial length of the rotating shaft is longer than the axial length of the stator assembly; the rotating shaft includes a rotating shaft main body, a protruding portion, and a transition portion connecting the rotating shaft main body and the protruding portion, the rotating shaft main body is axially located within the contour of the stator assembly, the protruding portion protrudes from the stator assembly, and the thickness of the protruding portion is larger than the thickness of the rotating shaft main body portion; a connecting portion is arranged on the inner surface of one end of the protruding portion for fixedly connecting with a chuck or an output spindle.

2. The electric tool according to claim 1, Characterized in that: The radial diameter of the protruding portion is 0.5 to 0.8 times the radial diameter of the rotating shaft main body.

3. The electric tool according to claim 2, Characterized in that: A connecting portion is arranged on the inner surface of the protruding portion, and the connecting portion includes a thread for fixedly connecting with a chuck or an output spindle.

4. The electric tool according to claim 1, Characterized in that: It includes a control circuit, and the control circuit includes a microcontroller, a detection module, and a control module; The detection module can detect motor parameters and output a detection signal to the microcontroller; The control module is electrically connected to the microcontroller and is used to change the direction of the motor current according to the signal of the microcontroller, control the forward or reverse rotation of the motor, and control the rotation speed of the motor.

5. An electric tool includes a housing composed of a cylindrical main body and a grip portion, and a plurality of components are axially accommodated in the main body. Characterized in that: It includes: A motor serving as a drive source; The motor includes a rotor assembly and a stator assembly, and the rotor assembly is located inside the stator assembly; the rotor assembly includes a rotating shaft with a cavity inside that rotates synchronously therewith; A reduction mechanism, at least part of which is arranged in the cavity of the rotating shaft; A first support bearing for rotatably supporting the rotor assembly, and the first support bearing is arranged in the cavity; the reduction mechanism includes a driving gear, which is arranged in the cavity of the rotating shaft and rotates synchronously with the rotating shaft; The rotor assembly further includes a first support portion, which is arranged in the cavity of the rotating shaft and rotates synchronously with the rotating shaft; One side of the center of the first support portion includes a first fixing portion for connecting the driving gear; the other side of the center of the first support portion includes a second fixing portion for connecting the first support bearing.

6. The electric tool according to claim 5, Characterized in that: The rotor assembly is located within the contour of the stator assembly.

7. The electric tool according to claim 5, Characterized in that: The first support portion is located within the contour of the stator assembly.

8. The electric tool according to claim 7, Characterized in that: The first support portion is substantially perpendicular to the axis direction of the rotating shaft.

9. The electric tool according to claim 5, Characterized in that: The driving gear is a sun gear, and the reduction mechanism further includes a plurality of planetary gears; The plurality of planetary gears are respectively fixed to the planet carrier through load-bearing pins, and the plurality of planetary gears are evenly arranged circumferentially along the planet carrier; The plurality of planetary gears are respectively meshed with the sun gear; Torque is transmitted between the sun gear and the planet carrier through the meshing connection of the planetary gears.

10. The power tool according to claim 9, wherein: The radial profile of the planet carrier is located within the radial profile of the rotating shaft.

11. The power tool according to claim 9, wherein: It includes a needle roller bearing configured between the inner side of the rotating shaft and the outer side of the planet carrier; and an internal gear ring configured on the outer side of the planet carrier and meshed with the plurality of planetary gears.

12. The power tool according to claim 11, wherein: The internal gear ring is fixedly connected or integrally provided with the main shaft locking disc.

13. The power tool according to claim 11, wherein: It includes an output main shaft, One side of the planet carrier is connected to the output main shaft for receiving the rotational torque of the reduction mechanism; A torque adjustment unit, one side of the torque adjustment unit is connected to the output main shaft, and the other side of the torque adjustment unit is connected to the chuck.

14. The power tool according to claim 13, wherein: It includes a clutch device configured between the planet carrier and the output main shaft.

15. The power tool according to claim 5, wherein: The reduction ratio of the reduction mechanism is between 3 and 10.

16. The power tool according to claim 5, wherein: The reduction ratio of the reduction mechanism is between 4 and 6.

17. The power tool according to claim 5, wherein: The radial profile of the reduction mechanism is within the radial profile of the motor.

18. The power tool according to any one of claims 5-17, wherein: It includes a control circuit, which includes a microcontroller, a detection module, and a control module; The detection module can detect motor parameters and output detection signals to the microcontroller; the control module is electrically connected to the microcontroller and is used to change the direction of the motor current, control the forward or reverse rotation of the motor, and control the rotation speed of the motor according to the signal of the microcontroller.

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